{"id":"CVE-2026-34230","aliases":["DEBIAN-CVE-2026-34230","EUVD-2026-18378","GHSA-v569-hp3g-36wr","MGASA-2026-0226","SUSE-SU-2026:1745-1","SUSE-SU-2026:1964-1","SUSE-SU-2026:23321-1","SUSE-SU-2026:2487-1","UBUNTU-CVE-2026-34230","USN-8989-1","openSUSE-SU-2026:10508-1","openSUSE-SU-2026:21640-1"],"status":"published","title":"Rack: Quadratic complexity in Rack::Utils.select_best_encoding via wildcard Accept-Encoding header","description":"Rack is a modular Ruby web server interface. Prior to versions 2.2.23, 3.1.21, and 3.2.6, Rack::Utils.select_best_encoding processes Accept-Encoding values with quadratic time complexity when the header contains many wildcard (*) entries. Because this method is used by Rack::Deflater to choose a response encoding, an unauthenticated attacker can send a single request with a crafted Accept-Encoding header and cause disproportionate CPU consumption on the compression middleware path. This results in a denial of service condition for applications using Rack::Deflater. This issue has been patched in versions 2.2.23, 3.1.21, and 3.2.6.","severity":{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L","level":"medium","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-11","score":0.00447,"percentile":0.39292,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-400","CWE-407"],"published":"2026-04-02T16:41:21Z","modified":"2026-11-04T03:43:07Z","fixes":[{"ecosystem":"RubyGems","package":"rack","fixed_in":["2.2.23","3.1.21","3.2.6"],"sources":["ghsa","osv"]},{"ecosystem":"Debian:12","package":"ruby-rack","fixed_in":["2.2.22-0+deb12u2"],"sources":["osv"]},{"ecosystem":"Debian:13","package":"ruby-rack","fixed_in":["3.1.20-0+deb13u2"],"sources":["osv"]},{"ecosystem":"Debian:14","package":"ruby-rack","fixed_in":["3.2.6-2"],"sources":["osv"]},{"ecosystem":"Ubuntu:Pro:14.04:LTS","package":"ruby-rack","fixed_in":["1.5.2-3+deb8u3ubuntu1~esm11"],"sources":["osv"]},{"ecosystem":"Ubuntu:Pro:16.04:LTS","package":"ruby-rack","fixed_in":["1.6.4-3ubuntu0.2+esm10"],"sources":["osv"]},{"ecosystem":"Ubuntu:Pro:18.04:LTS","package":"ruby-rack","fixed_in":["1.6.4-4ubuntu0.2+esm10"],"sources":["osv"]},{"ecosystem":"Ubuntu:Pro:22.04:LTS","package":"ruby-rack","fixed_in":["2.1.4-5ubuntu1.2+esm3"],"sources":["osv"]},{"ecosystem":"Ubuntu:24.04:LTS","package":"ruby-rack","fixed_in":["2.2.7-1ubuntu0.7"],"sources":["osv"]},{"ecosystem":"Ubuntu:25.10","package":"ruby-rack","fixed_in":["3.1.16-0.1ubuntu0.3"],"sources":["osv"]},{"ecosystem":"Ubuntu:26.04:LTS","package":"ruby-rack","fixed_in":["3.2.4-1ubuntu1.1"],"sources":["osv"]}],"affected":[{"source":"ghsa","ecosystem":"RubyGems","package":"rack","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.2.23"}]}]},{"source":"ghsa","ecosystem":"RubyGems","package":"rack","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"3.0.0.beta1"},{"fixed":"3.1.21"}]}]},{"source":"ghsa","ecosystem":"RubyGems","package":"rack","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"3.2.0"},{"fixed":"3.2.6"}]}]},{"source":"osv","ecosystem":"Debian:12","package":"ruby-rack","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.2.22-0+deb12u2"}]}],"versions":["2.2.13-1~deb12u1","2.2.20-0+deb12u1","2.2.22-0+deb12u1","2.2.6.4-1","2.2.6.4-1+deb12u1","2.2.7-1","2.2.7-1.1"]},{"source":"osv","ecosystem":"Debian:13","package":"ruby-rack","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.1.20-0+deb13u2"}]}],"versions":["3.1.16-0.1","3.1.18-1","3.1.18-1~deb13u1","3.1.20-0+deb13u1"]},{"source":"osv","ecosystem":"Debian:14","package":"ruby-rack","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.2.6-2"}]}],"versions":["3.1.16-0.1","3.1.18-1","3.1.18-1~deb13u1","3.2.4-1","3.2.5-1","3.2.5-2","3.2.6-1"]},{"source":"osv","ecosystem":"RubyGems","package":"rack","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.2.23"}]}],"versions":["0.1.0","0.2.0","0.3.0","0.4.0","0.9.0","0.9.1","1.0.0","1.0.1","1.1.0","1.1.1","1.1.1.pre","1.1.2","1.1.3","1.1.4","1.1.5","1.1.6","1.2.0","1.2.1","1.2.2","1.2.3","1.2.4","1.2.5","1.2.6","1.2.7","1.2.8","1.3.0","1.3.0.beta","1.3.0.beta2","1.3.1","1.3.10","1.3.2","1.3.3","1.3.4","1.3.5","1.3.6","1.3.7","1.3.8","1.3.9","1.4.0","1.4.1","1.4.2","1.4.3","1.4.4","1.4.5","1.4.6","1.4.7","1.5.0","1.5.0.beta.1","1.5.0.beta.2","1.5.1","1.5.2","1.5.3","1.5.4","1.5.5","1.6.0","1.6.0.beta","1.6.0.beta2","1.6.1","1.6.10","1.6.11","1.6.12","1.6.13","1.6.2","1.6.3","1.6.4","1.6.5","1.6.6","1.6.7","1.6.8","1.6.9","2.0.0.alpha","2.0.0.rc1","2.0.1","2.0.2","2.0.3","2.0.4","2.0.5","2.0.6","2.0.7","2.0.8","2.0.9","2.0.9.1","2.0.9.2","2.0.9.3","2.0.9.4","2.1.0","2.1.1","2.1.2","2.1.3","2.1.4","2.1.4.1","2.1.4.2","2.1.4.3","2.1.4.4","2.2.0","2.2.1","2.2.10","2.2.11","2.2.12","2.2.13","2.2.14","2.2.15","2.2.16","2.2.17","2.2.18","2.2.19","2.2.2","2.2.20","2.2.21","2.2.22","2.2.3","2.2.3.1","2.2.4","2.2.5","2.2.6","2.2.6.1","2.2.6.2","2.2.6.3","2.2.6.4","2.2.7","2.2.8","2.2.8.1","2.2.9"]},{"source":"osv","ecosystem":"RubyGems","package":"rack","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"3.0.0.beta1"},{"fixed":"3.1.21"}]}],"versions":["3.0.0","3.0.0.beta1","3.0.0.rc1","3.0.1","3.0.10","3.0.11","3.0.12","3.0.13","3.0.14","3.0.15","3.0.16","3.0.17","3.0.18","3.0.2","3.0.3","3.0.4","3.0.4.1","3.0.4.2","3.0.5","3.0.6","3.0.6.1","3.0.7","3.0.8","3.0.9","3.0.9.1","3.1.0","3.1.1","3.1.10","3.1.11","3.1.12","3.1.13","3.1.14","3.1.15","3.1.16","3.1.17","3.1.18","3.1.19","3.1.2","3.1.20","3.1.3","3.1.4","3.1.5","3.1.6","3.1.7","3.1.8","3.1.9"]},{"source":"osv","ecosystem":"RubyGems","package":"rack","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"3.2.0"},{"fixed":"3.2.6"}]}],"versions":["3.2.0","3.2.1","3.2.2","3.2.3","3.2.4","3.2.5"]},{"source":"osv","ecosystem":"Mageia:9","package":"ruby-rack","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.2.23-1.mga9"}]}],"bundled":12},{"source":"osv","ecosystem":"SUSE:Linux Enterprise Server 16.0","package":"rmt-server","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.1.0-160000.1.1"}]}],"bundled":10},{"source":"osv","ecosystem":"SUSE:Linux Enterprise Server for SAP applications 16.0","package":"rmt-server","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.1.0-160000.1.1"}]}],"bundled":10},{"source":"osv","ecosystem":"SUSE:Linux Enterprise Module for Public Cloud 15 SP5","package":"rmt-server","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.27-150500.3.47.1"}]}],"bundled":10},{"source":"osv","ecosystem":"SUSE:Linux Enterprise Module for Public Cloud 15 SP6","package":"rmt-server","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.27-150500.3.47.1"}]}],"bundled":10},{"source":"osv","ecosystem":"SUSE:Linux Enterprise High Performance Computing 15 SP5-ESPOS","package":"rmt-server","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.27-150500.3.47.1"}]}],"bundled":10},{"source":"osv","ecosystem":"SUSE:Linux Enterprise High Performance Computing 15 SP5-LTSS","package":"rmt-server","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.27-150500.3.47.1"}]}],"bundled":10},{"source":"osv","ecosystem":"SUSE:Linux Enterprise Server 15 SP5-LTSS","package":"rmt-server","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.27-150500.3.47.1"}]}],"bundled":10},{"source":"osv","ecosystem":"SUSE:Linux Enterprise Server 15 SP6-LTSS","package":"rmt-server","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.27-150500.3.47.1"}]}],"bundled":10},{"source":"osv","ecosystem":"SUSE:Linux Enterprise Server for SAP Applications 15 SP5","package":"rmt-server","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.27-150500.3.47.1"}]}],"bundled":10},{"source":"osv","ecosystem":"SUSE:Linux Enterprise Server for SAP Applications 15 SP6","package":"rmt-server","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.27-150500.3.47.1"}]}],"bundled":10},{"source":"osv","ecosystem":"Ubuntu:Pro:14.04:LTS","package":"ruby-rack","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.5.2-3+deb8u3ubuntu1~esm11"}]}],"versions":["1.5.2-1","1.5.2-1ubuntu0.1~esm1","1.5.2-3+deb8u3ubuntu1~esm2","1.5.2-3+deb8u3ubuntu1~esm3","1.5.2-3+deb8u3ubuntu1~esm4","1.5.2-3+deb8u3ubuntu1~esm6","1.5.2-3+deb8u3ubuntu1~esm7","1.5.2-3+deb8u3ubuntu1~esm8","1.5.2-3+deb8u3ubuntu1~esm9","1.5.2-3+deb8u3ubuntu1~esm10"]},{"source":"osv","ecosystem":"Ubuntu:Pro:16.04:LTS","package":"ruby-rack","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.6.4-3ubuntu0.2+esm10"}]}],"versions":["1.5.2-4","1.6.4-2","1.6.4-3","1.6.4-3ubuntu0.1","1.6.4-3ubuntu0.2","1.6.4-3ubuntu0.2+esm1","1.6.4-3ubuntu0.2+esm2","1.6.4-3ubuntu0.2+esm4","1.6.4-3ubuntu0.2+esm5","1.6.4-3ubuntu0.2+esm6","1.6.4-3ubuntu0.2+esm7","1.6.4-3ubuntu0.2+esm8","1.6.4-3ubuntu0.2+esm9"]},{"source":"osv","ecosystem":"Ubuntu:Pro:18.04:LTS","package":"ruby-rack","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.6.4-4ubuntu0.2+esm10"}]}],"versions":["1.6.4-4","1.6.4-4ubuntu0.1","1.6.4-4ubuntu0.2","1.6.4-4ubuntu0.2+esm1","1.6.4-4ubuntu0.2+esm2","1.6.4-4ubuntu0.2+esm4","1.6.4-4ubuntu0.2+esm5","1.6.4-4ubuntu0.2+esm6","1.6.4-4ubuntu0.2+esm7","1.6.4-4ubuntu0.2+esm8","1.6.4-4ubuntu0.2+esm9"]},{"source":"osv","ecosystem":"Ubuntu:Pro:22.04:LTS","package":"ruby-rack","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.1.4-5ubuntu1.2+esm3"}]}],"versions":["2.1.4-3","2.1.4-4","2.1.4-5","2.1.4-5ubuntu1","2.1.4-5ubuntu1+esm2","2.1.4-5ubuntu1+esm3","2.1.4-5ubuntu1+esm4","2.1.4-5ubuntu1+esm5","2.1.4-5ubuntu1.1","2.1.4-5ubuntu1.1+esm1","2.1.4-5ubuntu1.1+esm2","2.1.4-5ubuntu1.2","2.1.4-5ubuntu1.2+esm1","2.1.4-5ubuntu1.2+esm2"]},{"source":"osv","ecosystem":"Ubuntu:24.04:LTS","package":"ruby-rack","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.2.7-1ubuntu0.7"}]}],"versions":["2.2.4-3","2.2.7-1","2.2.7-1ubuntu0.1","2.2.7-1ubuntu0.2","2.2.7-1ubuntu0.3","2.2.7-1ubuntu0.4","2.2.7-1ubuntu0.5","2.2.7-1ubuntu0.6"]},{"source":"osv","ecosystem":"Ubuntu:25.10","package":"ruby-rack","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.1.16-0.1ubuntu0.3"}]}],"versions":["2.2.7-1.1","3.1.16-0.1","3.1.16-0.1ubuntu0.1","3.1.16-0.1ubuntu0.2"]},{"source":"osv","ecosystem":"Ubuntu:26.04:LTS","package":"ruby-rack","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.2.4-1ubuntu1.1"}]}],"versions":["3.1.16-0.1","3.1.18-1","3.1.18-1build1","3.2.4-1ubuntu1"]},{"source":"osv","ecosystem":"Ubuntu:26.04:LTS","package":"ruby-rack","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.2.4-1ubuntu1.1"}]}],"versions":["3.1.16-0.1","3.1.18-1","3.1.18-1build1","3.2.4-1ubuntu1"],"bundled":13},{"source":"osv","ecosystem":"openSUSE:Tumbleweed","package":"rubygem-rack-2.2","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.2.23-1.1"}]}],"bundled":9},{"source":"osv","ecosystem":"openSUSE:Leap 16.0","package":"rmt-server","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.1.0-160000.1.1"}]}],"bundled":10}],"products":[{"vendor":"rack","product":"rack"}],"references":[{"url":"https://github.com/rack/rack/security/advisories/GHSA-v569-hp3g-36wr","tags":["x_refsource_CONFIRM","Vendor Advisory","advisory","web","report"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-34230","tags":["advisory"]},{"url":"https://github.com/rubysec/ruby-advisory-db/blob/master/gems/rack/CVE-2026-34230.yml","tags":["web"]},{"url":"https://github.com/advisories/GHSA-v569-hp3g-36wr"},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/34xxx/CVE-2026-34230.json","tags":["advisory"]},{"url":"https://security-tracker.debian.org/tracker/CVE-2026-34230","tags":["advisory"]},{"url":"https://github.com/rack/rack","tags":["package"]},{"url":"https://advisories.mageia.org/MGASA-2026-0226.html","tags":["advisory"]},{"url":"https://bugs.mageia.org/show_bug.cgi?id=35446","tags":["report"]},{"url":"https://github.com/rack/rack/security/advisories/GHSA-vgpv-f759-9wx3","tags":["advisory"]},{"url":"https://github.com/rack/rack/security/advisories/GHSA-qfgr-crr9-7r49","tags":["advisory"]},{"url":"https://github.com/rack/rack/security/advisories/GHSA-7mqq-6cf9-v2qp","tags":["advisory"]},{"url":"https://github.com/rack/rack/security/advisories/GHSA-h2jq-g4cq-5ppq","tags":["advisory"]},{"url":"https://github.com/rack/rack/security/advisories/GHSA-q4qf-9j86-f5mh","tags":["advisory"]},{"url":"https://github.com/rack/rack/security/advisories/GHSA-x8cg-fq8g-mxfx","tags":["advisory"]},{"url":"https://github.com/rack/rack/security/advisories/GHSA-v6x5-cg8r-vv6x","tags":["advisory"]},{"url":"https://github.com/rack/rack/security/advisories/GHSA-8vqr-qjwx-82mw","tags":["advisory"]},{"url":"https://github.com/rack/rack/security/advisories/GHSA-qv7j-4883-hwh7","tags":["advisory"]},{"url":"https://github.com/rack/rack/security/advisories/GHSA-q2ww-5357-x388","tags":["advisory"]},{"url":"https://github.com/rack/rack/security/advisories/GHSA-g2pf-xv49-m2h5","tags":["advisory"]},{"url":"https://www.suse.com/support/update/announcement/2026/suse-su-20261745-1/","tags":["advisory"]},{"url":"https://bugzilla.suse.com/1261388","tags":["report"]},{"url":"https://bugzilla.suse.com/1261398","tags":["report"]},{"url":"https://bugzilla.suse.com/1261406","tags":["report"]},{"url":"https://bugzilla.suse.com/1261417","tags":["report"]},{"url":"https://bugzilla.suse.com/1261426","tags":["report"]},{"url":"https://bugzilla.suse.com/1261436","tags":["report"]},{"url":"https://bugzilla.suse.com/1261447","tags":["report"]},{"url":"https://bugzilla.suse.com/1261458","tags":["report"]},{"url":"https://bugzilla.suse.com/1261466","tags":["report"]},{"url":"https://bugzilla.suse.com/1261471","tags":["report"]},{"url":"https://www.suse.com/security/cve/CVE-2026-26961","tags":["web"]},{"url":"https://www.suse.com/security/cve/CVE-2026-26962","tags":["web"]},{"url":"https://www.suse.com/security/cve/CVE-2026-34230","tags":["web"]},{"url":"https://www.suse.com/security/cve/CVE-2026-34763","tags":["web"]},{"url":"https://www.suse.com/security/cve/CVE-2026-34785","tags":["web"]},{"url":"https://www.suse.com/security/cve/CVE-2026-34786","tags":["web"]},{"url":"https://www.suse.com/security/cve/CVE-2026-34826","tags":["web"]},{"url":"https://www.suse.com/security/cve/CVE-2026-34829","tags":["web"]},{"url":"https://www.suse.com/security/cve/CVE-2026-34830","tags":["web"]},{"url":"https://www.suse.com/security/cve/CVE-2026-34831","tags":["web"]},{"url":"https://www.suse.com/support/update/announcement/2026/suse-su-20261964-1/","tags":["advisory"]},{"url":"https://bugzilla.suse.com/1246976","tags":["report"]},{"url":"https://www.suse.com/support/update/announcement/2026/suse-su-202623321-1/","tags":["advisory"]},{"url":"https://bugzilla.suse.com/1262706","tags":["report"]},{"url":"https://bugzilla.suse.com/1268149","tags":["report"]},{"url":"https://bugzilla.suse.com/1268301","tags":["report"]},{"url":"https://bugzilla.suse.com/1268303","tags":["report"]},{"url":"https://bugzilla.suse.com/1268305","tags":["report"]},{"url":"https://bugzilla.suse.com/1274715","tags":["report"]},{"url":"https://www.suse.com/support/update/announcement/2026/suse-su-20262487-1/","tags":["advisory"]},{"url":"https://ubuntu.com/security/CVE-2026-34230","tags":["report"]},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-34230","tags":["report"]},{"url":"https://ubuntu.com/security/notices/USN-8182-1","tags":["advisory"]},{"url":"https://ubuntu.com/security/notices/USN-8989-1","tags":["advisory"]},{"url":"https://ubuntu.com/security/CVE-2026-26961","tags":["report"]},{"url":"https://ubuntu.com/security/CVE-2026-26962","tags":["report"]},{"url":"https://ubuntu.com/security/CVE-2026-32762","tags":["report"]},{"url":"https://ubuntu.com/security/CVE-2026-34763","tags":["report"]},{"url":"https://ubuntu.com/security/CVE-2026-34785","tags":["report"]},{"url":"https://ubuntu.com/security/CVE-2026-34786","tags":["report"]},{"url":"https://ubuntu.com/security/CVE-2026-34826","tags":["report"]},{"url":"https://ubuntu.com/security/CVE-2026-34827","tags":["report"]},{"url":"https://ubuntu.com/security/CVE-2026-34829","tags":["report"]},{"url":"https://ubuntu.com/security/CVE-2026-34830","tags":["report"]},{"url":"https://ubuntu.com/security/CVE-2026-34831","tags":["report"]},{"url":"https://ubuntu.com/security/CVE-2026-34835","tags":["report"]},{"url":"","tags":["advisory"]}],"sources":{"cve":[{"id":"CVE-2026-34230","title":"Rack: Quadratic complexity in Rack::Utils.select_best_encoding via wildcard Accept-Encoding header","description":"Rack is a modular Ruby web server interface. Prior to versions 2.2.23, 3.1.21, and 3.2.6, Rack::Utils.select_best_encoding processes Accept-Encoding values with quadratic time complexity when the header contains many wildcard (*) entries. Because this method is used by Rack::Deflater to choose a response encoding, an unauthenticated attacker can send a single request with a crafted Accept-Encoding header and cause disproportionate CPU consumption on the compression middleware path. This results in a denial of service condition for applications using Rack::Deflater. This issue has been patched in versions 2.2.23, 3.1.21, and 3.2.6.","status":"published","published":"2026-04-02T16:41:21.095Z","modified":"2026-04-03T18:19:00.388Z","cvss":[{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L","level":"medium","assessor":"cna"}],"cwes":["CWE-400","CWE-407"],"updated_at":"2026-11-02T14:20:13.962274Z"}],"euvd":[{"id":"EUVD-2026-18378","description":"Rack is a modular Ruby web server interface. Prior to versions 2.2.23, 3.1.21, and 3.2.6, Rack::Utils.select_best_encoding processes Accept-Encoding values with quadratic time complexity when the header contains many wildcard (*) entries. Because this method is used by Rack::Deflater to choose a response encoding, an unauthenticated attacker can send a single request with a crafted Accept-Encoding header and cause disproportionate CPU consumption on the compression middleware path. This results in a denial of service condition for applications using Rack::Deflater. This issue has been patched in versions 2.2.23, 3.1.21, and 3.2.6.","status":"published","published":"2026-04-02T16:41:21Z","modified":"2026-04-03T18:19:00Z","cvss":[{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L","level":"medium"}],"updated_at":"2026-11-02T19:25:16.550278Z"}],"ghsa":[{"id":"GHSA-v569-hp3g-36wr","title":"Rack has quadratic complexity in Rack::Utils.select_best_encoding via wildcard Accept-Encoding header","description":"## Summary\n\n`Rack::Utils.select_best_encoding` processes `Accept-Encoding` values with quadratic time complexity when the header contains many wildcard (`*`) entries. Because this method is used by `Rack::Deflater` to choose a response encoding, an unauthenticated attacker can send a single request with a crafted `Accept-Encoding` header and cause disproportionate CPU consumption on the compression middleware path.\n\nThis results in a denial of service condition for applications using `Rack::Deflater`.\n\n## Details\n\n`Rack::Utils.select_best_encoding` expands parsed `Accept-Encoding` values into a list of candidate encodings. When an entry is `*`, the method computes the set of concrete encodings by subtracting the encodings already present in the request:\n\n```ruby\nif m == \"*\"\n  (available_encodings - accept_encoding.map(\u0026:first)).each do |m2|\n    expanded_accept_encoding \u003c\u003c [m2, q, preference]\n  end\nelse\n  expanded_accept_encoding \u003c\u003c [m, q, preference]\nend\n```\n\nBecause `accept_encoding.map(\u0026:first)` is evaluated inside the loop, it is recomputed for each wildcard entry. If the request contains `N` wildcard entries, this produces repeated scans over the full parsed header and causes quadratic behavior.\n\nAfter expansion, the method also performs additional work over `expanded_accept_encoding`, including per-entry deletion, which further increases the cost for large inputs.\n\n`Rack::Deflater` invokes this method for each request when the middleware is enabled:\n\n```ruby\nUtils.select_best_encoding(ENCODINGS, Utils.parse_encodings(accept_encoding))\n```\n\nAs a result, a client can trigger this expensive code path simply by sending a large `Accept-Encoding` header containing many repeated wildcard values.\n\nFor example, a request with an approximately 8 KB `Accept-Encoding` header containing about 1,000 `*;q=0.5` entries can cause roughly 170 ms of CPU time in a single request on the `Rack::Deflater` path, compared to a negligible baseline for a normal header.\n\nThis issue is distinct from CVE-2024-26146. That issue concerned regular expression denial of service during `Accept` header parsing, whereas this issue arises later during encoding selection after the header has already been parsed.\n\n## Impact\n\nAny Rack application using `Rack::Deflater` may be affected.\n\nAn unauthenticated attacker can send requests with crafted `Accept-Encoding` headers to trigger excessive CPU usage in the encoding selection logic. Repeated requests can consume worker time disproportionately and reduce application availability.\n\nThe attack does not require invalid HTTP syntax or large payload bodies. A single header-sized request is sufficient to reach the vulnerable code path.\n\n## Mitigation\n\n* Update to a patched version of Rack in which encoding selection does not repeatedly rescan the parsed header for wildcard entries.\n* Avoid enabling `Rack::Deflater` on untrusted traffic.\n* Apply request filtering or header size / format restrictions at the reverse proxy or application boundary to limit abusive `Accept-Encoding` values.","status":"published","published":"2026-04-02T20:32:19Z","modified":"2026-05-13T16:18:13Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high"}],"cwes":["CWE-400","CWE-407"],"updated_at":"2026-11-02T14:40:08.003212Z"}],"nvd":[{"id":"CVE-2026-34230","description":"Rack is a modular Ruby web server interface. Prior to versions 2.2.23, 3.1.21, and 3.2.6, Rack::Utils.select_best_encoding processes Accept-Encoding values with quadratic time complexity when the header contains many wildcard (*) entries. Because this method is used by Rack::Deflater to choose a response encoding, an unauthenticated attacker can send a single request with a crafted Accept-Encoding header and cause disproportionate CPU consumption on the compression middleware path. This results in a denial of service condition for applications using Rack::Deflater. This issue has been patched in versions 2.2.23, 3.1.21, and 3.2.6.","status":"published","published":"2026-04-02T17:16:23.57Z","modified":"2026-07-24T21:10:00.143Z","cvss":[{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L","level":"medium","assessor":"secondary"},{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high","assessor":"primary"}],"cwes":["CWE-400","CWE-407"],"updated_at":"2026-11-02T14:12:12.73929Z"}],"osv":[{"id":"CVE-2026-34230","title":"Rack: Quadratic complexity in Rack::Utils.select_best_encoding via wildcard Accept-Encoding header","description":"Rack is a modular Ruby web server interface. Prior to versions 2.2.23, 3.1.21, and 3.2.6, Rack::Utils.select_best_encoding processes Accept-Encoding values with quadratic time complexity when the header contains many wildcard (*) entries. Because this method is used by Rack::Deflater to choose a response encoding, an unauthenticated attacker can send a single request with a crafted Accept-Encoding header and cause disproportionate CPU consumption on the compression middleware path. This results in a denial of service condition for applications using Rack::Deflater. This issue has been patched in versions 2.2.23, 3.1.21, and 3.2.6.","status":"published","published":"2026-04-02T16:41:21.095Z","modified":"2026-10-28T02:31:04.009382309Z","cvss":[{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L","level":"medium"}],"cwes":["CWE-400","CWE-407"],"updated_at":"2026-11-02T15:45:02.247031Z"},{"id":"DEBIAN-CVE-2026-34230","description":"Rack is a modular Ruby web server interface. Prior to versions 2.2.23, 3.1.21, and 3.2.6, Rack::Utils.select_best_encoding processes Accept-Encoding values with quadratic time complexity when the header contains many wildcard (*) entries. Because this method is used by Rack::Deflater to choose a response encoding, an unauthenticated attacker can send a single request with a crafted Accept-Encoding header and cause disproportionate CPU consumption on the compression middleware path. This results in a denial of service condition for applications using Rack::Deflater. This issue has been patched in versions 2.2.23, 3.1.21, and 3.2.6.","status":"published","published":"2026-04-02T17:16:23.57Z","modified":"2026-10-01T03:02:37.445052369Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high"}],"updated_at":"2026-11-02T15:45:54.587575Z"},{"id":"GHSA-v569-hp3g-36wr","title":"Rack has quadratic complexity in Rack::Utils.select_best_encoding via wildcard Accept-Encoding header","description":"## Summary\n\n`Rack::Utils.select_best_encoding` processes `Accept-Encoding` values with quadratic time complexity when the header contains many wildcard (`*`) entries. Because this method is used by `Rack::Deflater` to choose a response encoding, an unauthenticated attacker can send a single request with a crafted `Accept-Encoding` header and cause disproportionate CPU consumption on the compression middleware path.\n\nThis results in a denial of service condition for applications using `Rack::Deflater`.\n\n## Details\n\n`Rack::Utils.select_best_encoding` expands parsed `Accept-Encoding` values into a list of candidate encodings. When an entry is `*`, the method computes the set of concrete encodings by subtracting the encodings already present in the request:\n\n```ruby\nif m == \"*\"\n  (available_encodings - accept_encoding.map(\u0026:first)).each do |m2|\n    expanded_accept_encoding \u003c\u003c [m2, q, preference]\n  end\nelse\n  expanded_accept_encoding \u003c\u003c [m, q, preference]\nend\n```\n\nBecause `accept_encoding.map(\u0026:first)` is evaluated inside the loop, it is recomputed for each wildcard entry. If the request contains `N` wildcard entries, this produces repeated scans over the full parsed header and causes quadratic behavior.\n\nAfter expansion, the method also performs additional work over `expanded_accept_encoding`, including per-entry deletion, which further increases the cost for large inputs.\n\n`Rack::Deflater` invokes this method for each request when the middleware is enabled:\n\n```ruby\nUtils.select_best_encoding(ENCODINGS, Utils.parse_encodings(accept_encoding))\n```\n\nAs a result, a client can trigger this expensive code path simply by sending a large `Accept-Encoding` header containing many repeated wildcard values.\n\nFor example, a request with an approximately 8 KB `Accept-Encoding` header containing about 1,000 `*;q=0.5` entries can cause roughly 170 ms of CPU time in a single request on the `Rack::Deflater` path, compared to a negligible baseline for a normal header.\n\nThis issue is distinct from CVE-2024-26146. That issue concerned regular expression denial of service during `Accept` header parsing, whereas this issue arises later during encoding selection after the header has already been parsed.\n\n## Impact\n\nAny Rack application using `Rack::Deflater` may be affected.\n\nAn unauthenticated attacker can send requests with crafted `Accept-Encoding` headers to trigger excessive CPU usage in the encoding selection logic. Repeated requests can consume worker time disproportionately and reduce application availability.\n\nThe attack does not require invalid HTTP syntax or large payload bodies. A single header-sized request is sufficient to reach the vulnerable code path.\n\n## Mitigation\n\n* Update to a patched version of Rack in which encoding selection does not repeatedly rescan the parsed header for wildcard entries.\n* Avoid enabling `Rack::Deflater` on untrusted traffic.\n* Apply request filtering or header size / format restrictions at the reverse proxy or application boundary to limit abusive `Accept-Encoding` values.","status":"published","published":"2026-04-02T20:32:19Z","modified":"2026-09-10T03:51:03.178734762Z","cvss":[{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high"}],"cwes":["CWE-400","CWE-407"],"updated_at":"2026-11-02T15:46:56.639206Z"},{"id":"UBUNTU-CVE-2026-34230","description":"Rack is a modular Ruby web server interface. Prior to versions 2.2.23, 3.1.21, and 3.2.6, Rack::Utils.select_best_encoding processes Accept-Encoding values with quadratic time complexity when the header contains many wildcard (*) entries. Because this method is used by Rack::Deflater to choose a response encoding, an unauthenticated attacker can send a single request with a crafted Accept-Encoding header and cause disproportionate CPU consumption on the compression middleware path. This results in a denial of service condition for applications using Rack::Deflater. This issue has been patched in versions 2.2.23, 3.1.21, and 3.2.6.","status":"published","published":"2026-04-02T17:16:00Z","modified":"2026-11-04T03:42:04.324361806Z","cvss":[{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L","level":"medium"},{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high"}],"updated_at":"2026-11-04T03:56:18.279609Z"},{"id":"MGASA-2026-0226","title":"Updated ruby-rack packages fix security vulnerabilities","description":"CVE-2026-26961 Greedy multipart boundary parsing can cause parser\ndifferentials and WAF bypass. `Forwarded` header semicolon injection\nenables `Host` and `Scheme` spoofing.\nCVE-2026-34230 Quadratic complexity in\n`Rack::Utils.select_best_encoding` via wildcard `Accept-Encoding`\nheader.\nCVE-2026-34763 Root directory disclosure via unescaped regex\ninterpolation in `Rack::Directory`.\nCVE-2026-34785 `Rack::Static` prefix matching can expose unintended\nfiles under the static root.\nCVE-2026-34786 `Rack::Static` `header_rules` bypass via URL-encoded path\nmismatch.\nCVE-2026-34826 Multipart byte range processing allows denial of service\nvia excessive overlapping ranges.\nCVE-2026-34827 Multipart header parsing allows denial of service via\nescape-heavy quoted parameters.\nCVE-2026-34829 Multipart parsing without `Content-Length` header allows\nunbounded chunked file uploads.\nCVE-2026-34830 `Rack::Sendfile` header-based `X-Accel-Mapping` regex\ninjection enables unauthorized `X-Accel-Redirect`.\nCVE-2026-34831 `Content-Length` mismatch in `Rack::Files` error\nresponses.\nCVE-2026-34835 `Rack::Request` accepts invalid Host characters, enabling\nhost allowlist bypass.\n","status":"published","published":"2026-06-18T21:28:22Z","modified":"2026-06-18T21:30:04.563755676Z","updated_at":"2026-11-02T15:49:43.795591Z"},{"id":"openSUSE-SU-2026:10508-1","title":"ruby4.0-rubygem-rack-2.2-2.2.23-1.1 on GA media","description":"These are all security issues fixed in the ruby4.0-rubygem-rack-2.2-2.2.23-1.1 package on the GA media of openSUSE Tumbleweed.","status":"published","published":"2026-04-08T00:00:00Z","modified":"2026-04-09T08:01:09.703554Z","updated_at":"2026-11-02T16:58:38.415593Z"},{"id":"openSUSE-SU-2026:21640-1","title":"Security update for rmt-server","description":"This update for rmt-server fixes the following issues:\n\nUpdate to version 3.1 (bsc#1274715).\n\nSecurity issues fixed:\n\n- CVE-2026-26961: rack: greedy multipart boundary parsing can lead to parser differentials and WAF bypass\n  (bsc#1261398).\n- CVE-2026-26962: rack: improper unfolding of folded multipart headers can lead to downstream header injection and\n  response splitting(bsc#1261471).\n- CVE-2026-34763: rack: unescaped regex interpolation of configured root path can lead to root directory disclosure\n  (bsc#1261406).\n- CVE-2026-34230: rack: crafted `Accept-Encoding` headers can cause a denial of service (bsc#1261388).\n- CVE-2026-34785: rack: prefix matching logic can lead to the exposure of unintended files under the static root\n  (bsc#1261417).\n- CVE-2026-34786: rack: URL-encoded path mismatch can lead to `header_rules` bypass (bsc#1261426).\n- CVE-2026-34826: rack: missing individual byte range limit checks when parsing HTTP `Range` headers can lead to\n  excessive resource consumption and a denial of service (bsc#1261436).\n- CVE-2026-34829: rack: multipart parsing without `Content-Length` header can lead to unbounded chunked file uploads\n  and a denial of service (bsc#1261447).\n- CVE-2026-34230: rack: quadratic complexity when processing of wildcard `Accept-Encoding` headers can lead to a denial\n  of service (bsc#1261388).\n- CVE-2026-34830: rack: improper sanitization of the `X-Accel-Mapping` request header can lead to the exposure of\n  unintended files via `X-Accel-Redirect` (bsc#1261458).\n- CVE-2026-34831: rack: `Content-Length` header and body byte size mismatch when creating error responses can lead to\n  incorrect HTTP response framing (bsc#1261466).\n\nOther updates and bugfixes:\n\n- Version 3.1:\n  * Remove all errors and warnigs due to new Ruby and Ruby on Rails versions\n- Version 2.28:\n  * Set arch to unknown for Rancher based products (jsc#SCC-759)\n  * Fix purge for large amount of systems (bsc#1262706)\n  * Change data type to `MEDIUMTEXT` in profiles table (bsc#1268305)\n  * Remove `proxy_byos` column\n  * Fix race condition when no system matches (bsc#1268301)\n  * Fix race condition for PAYG (bsc#1268149)\n  * Fix race condition to update a system (bsc#1268303)\n- Version 2.27:\n  * Fix ReDoS vulnerability in `Addressable`\n  * Fixes out-of-bounds read vulnerability in `rdiscount`\n","status":"published","published":"2026-08-25T06:34:56Z","modified":"2026-08-27T18:23:12.978274573Z","updated_at":"2026-11-02T16:58:41.885092Z"},{"id":"SUSE-SU-2026:1745-1","title":"Security update for rmt-server","description":"This update for rmt-server fixes the following issues:\n\nUpdate to version 2.27.\n\nSecurity issues fixed:\n\n- CVE-2026-26961: rack: greedy multipart boundary parsing can lead to parser differentials and WAF bypass\n  (bsc#1261398).\n- CVE-2026-26962: rack: improper unfolding of folded multipart headers can lead to downstream header injection and\n  response splitting(bsc#1261471).  \n- CVE-2026-34763: rack: unescaped regex interpolation of configured root path can lead to root directory disclosure\n  (bsc#1261406).\n- CVE-2026-34785: rack: prefix matching logic can lead to the exposure of unintended files under the static root\n  (bsc#1261417).\n- CVE-2026-34786: rack: URL-encoded path mismatch can lead to `header_rules` bypass (bsc#1261426).\n- CVE-2026-34826: rack: missing individual byte range limit checks when parsing HTTP `Range` headers can lead to\n  excessive resource consumption and a denial of service (bsc#1261436).\n- CVE-2026-34829: rack: multipart parsing without `Content-Length` header can lead to unbounded chunked file uploads\n  and a denial of service (bsc#1261447).\n- CVE-2026-34230: rack: quadratic complexity when processing of wildcard `Accept-Encoding` headers can lead to a denial\n  of service (bsc#1261388).  \n- CVE-2026-34830: rack: improper sanitization of the `X-Accel-Mapping` request header can lead to the exposure of\n  unintended files via `X-Accel-Redirect` (bsc#1261458).\n- CVE-2026-34831: rack: `Content-Length` header and body byte size mismatch when creating error responses can lead to\n  incorrect HTTP response framing (bsc#1261466).\n\nOther updates and bugfixes:\n\n- Fix ReDoS in `Addressable`.\n- Fix out-of-bounds read in `rdiscount`.\n","status":"published","published":"2026-05-07T07:22:43Z","modified":"2026-05-08T08:15:48.775796Z","updated_at":"2026-11-02T15:54:01.610851Z"},{"id":"SUSE-SU-2026:1964-1","title":"Security update for rmt-server","description":"This update for rmt-server fixes the following issues\n\n- CVE-2026-26961: rack: mismatch in header handling can allow to smuggle multipart content (bsc#1261398).\n- CVE-2026-26962: rack: improper unfolding of folded multipart headers can lead to header injection or response\n  splitting (bsc#1261471).\n- CVE-2026-34230: rack: crafted Accept-Encoding header can cause a denial of service (bsc#1261388).\n- CVE-2026-34763: rack: failing of the prefix stripping can lead to information disclosure (bsc#1261406).\n- CVE-2026-34785: rack: prefix matching can expose unintended files under the static root (bsc#1261417).\n- CVE-2026-34786: rack: URL-encoded path mismatch can lead to `header_rules` bypass (bsc#1261426).\n- CVE-2026-34826: rack: multipart byte range processing can allow denial of service (bsc#1261436).\n- CVE-2026-34829: rack: multipart parsing without `Content-Length` header allows unbounded chunked file uploads\n  (bsc#1261447).\n- CVE-2026-34830: rack: crafted `X-Accel-Mapping`headers can lead to regex injection (bsc#1261458).\n- CVE-2026-34831: rack: `Content-Length` mismatch can lead to incorrectly framed error responses (bsc#1261466).\n\nOther fixes:\n\n- Update to version 2.27\n","status":"published","published":"2026-05-18T08:10:04Z","modified":"2026-05-19T08:45:12.089394872Z","updated_at":"2026-11-02T15:54:01.610851Z"},{"id":"SUSE-SU-2026:23321-1","title":"Security update for rmt-server","description":"This update for rmt-server fixes the following issues:\n\nUpdate to version 3.1 (bsc#1274715).\n\nSecurity issues fixed:\n\n- CVE-2026-26961: rack: greedy multipart boundary parsing can lead to parser differentials and WAF bypass\n  (bsc#1261398).\n- CVE-2026-26962: rack: improper unfolding of folded multipart headers can lead to downstream header injection and\n  response splitting(bsc#1261471).\n- CVE-2026-34763: rack: unescaped regex interpolation of configured root path can lead to root directory disclosure\n  (bsc#1261406).\n- CVE-2026-34230: rack: crafted `Accept-Encoding` headers can cause a denial of service (bsc#1261388).\n- CVE-2026-34785: rack: prefix matching logic can lead to the exposure of unintended files under the static root\n  (bsc#1261417).\n- CVE-2026-34786: rack: URL-encoded path mismatch can lead to `header_rules` bypass (bsc#1261426).\n- CVE-2026-34826: rack: missing individual byte range limit checks when parsing HTTP `Range` headers can lead to\n  excessive resource consumption and a denial of service (bsc#1261436).\n- CVE-2026-34829: rack: multipart parsing without `Content-Length` header can lead to unbounded chunked file uploads\n  and a denial of service (bsc#1261447).\n- CVE-2026-34230: rack: quadratic complexity when processing of wildcard `Accept-Encoding` headers can lead to a denial\n  of service (bsc#1261388).\n- CVE-2026-34830: rack: improper sanitization of the `X-Accel-Mapping` request header can lead to the exposure of\n  unintended files via `X-Accel-Redirect` (bsc#1261458).\n- CVE-2026-34831: rack: `Content-Length` header and body byte size mismatch when creating error responses can lead to\n  incorrect HTTP response framing (bsc#1261466).\n\nOther updates and bugfixes:\n\n- Version 3.1:\n  * Remove all errors and warnigs due to new Ruby and Ruby on Rails versions\n- Version 2.28:\n  * Set arch to unknown for Rancher based products (jsc#SCC-759)\n  * Fix purge for large amount of systems (bsc#1262706)\n  * Change data type to `MEDIUMTEXT` in profiles table (bsc#1268305)\n  * Remove `proxy_byos` column\n  * Fix race condition when no system matches (bsc#1268301)\n  * Fix race condition for PAYG (bsc#1268149)\n  * Fix race condition to update a system (bsc#1268303)\n- Version 2.27:\n  * Fix ReDoS vulnerability in `Addressable`\n  * Fixes out-of-bounds read vulnerability in `rdiscount`\n","status":"published","published":"2026-08-25T06:34:19Z","modified":"2026-09-10T18:23:10.500108459Z","updated_at":"2026-11-02T15:54:03.503431Z"},{"id":"SUSE-SU-2026:2487-1","title":"Security update for rmt-server","description":"This update for rmt-server fixes the following issues\n\n- CVE-2026-26961: rack: mismatch in header handling can allow to smuggle multipart content (bsc#1261398).\n- CVE-2026-26962: rack: improper unfolding of folded multipart headers can lead to header injection or response\n  splitting (bsc#1261471).\n- CVE-2026-34230: rack: crafted Accept-Encoding header can cause a denial of service (bsc#1261388).\n- CVE-2026-34763: rack: failing of the prefix stripping can lead to information disclosure (bsc#1261406).\n- CVE-2026-34785: rack: prefix matching can expose unintended files under the static root (bsc#1261417).\n- CVE-2026-34786: rack: URL-encoded path mismatch can lead to `header_rules` bypass (bsc#1261426).\n- CVE-2026-34826: rack: multipart byte range processing can allow denial of service (bsc#1261436).\n- CVE-2026-34829: rack: multipart parsing without `Content-Length` header allows unbounded chunked file uploads\n  (bsc#1261447).\n- CVE-2026-34830: rack: crafted `X-Accel-Mapping`headers can lead to regex injection (bsc#1261458).\n- CVE-2026-34831: rack: `Content-Length` mismatch can lead to incorrectly framed error responses (bsc#1261466).\n\nChanges for rmt-server:\n\n- Updated to version 2.27\n","status":"published","published":"2026-06-22T12:08:31Z","modified":"2026-06-24T09:00:14.591265313Z","updated_at":"2026-11-02T15:54:04.519245Z"},{"id":"USN-8989-1","title":"ruby-rack vulnerabilities","description":"Andrew Lacambra discovered that Rack did not properly parse certain regular\nexpressions. An attacker could possibly use this issue to bypass network\nsecurity filters. (CVE-2026-26961)\n\nWilliam T. Nelson discovered that Rack did not handle multipart headers\ncorrectly. An attacker could possibly use this issue to cause downstream\nparsing issues or a denial of service. (CVE-2026-26962)\n\nIt was discovered that Rack did not handle the Forwarded header correctly.\nAn attacker could possibly use this issue to manipulate header values.\n(CVE-2026-32762)\n\nIt was discovered that Rack could consume excessive CPU when handling\ncertain Accept-Encoding values. An attacker could possibly use this issue\nto cause a denial of service. (CVE-2026-34230)\n\nHaruki Oyama discovered that certain configurations of Rack could\nerroneously fail to derive the displayed directory path, and expose the\nfull file system path. An attacker could possibly use this issue to\ndisclose deployment details such as layout and usernames. (CVE-2026-34763)\n\nIt was discovered that Rack did not properly handle static file paths. An\nattacker could possibly use this issue to exfiltrate unintentionally served\ndata. (CVE-2026-34785)\n\nHaruki Oyama discovered that Rack did not apply header rules to certain\nrequests for URL-encoded static paths. An attacker could possibly use this\nissue to bypass security-relevant response headers. (CVE-2026-34786)\n\nIt was discovered that Rack did not limit the number of ranges requested in\nthe Range header. An attacker could possibly use this issue to cause a\ndenial of service. (CVE-2026-34826)\n\nIt was discovered that Rack could consume excessive CPU when parsing\ncertain multipart parameters. An attacker could possibly use this issue to\ncause a denial of service. (CVE-2026-34827)\n\nIt was discovered that Rack could consume unbounded disk space when\nhandling requests without a Content-Length header. An attacker could\npossibly use this issue to cause a denial of service. (CVE-2026-34829)\n\nMehtab Zafar discovered that Rack directly interpreted the X-Accel-Mapping\nheader as a regular expression without escaping. An attacker could possibly\nuse this issue to exfiltrate arbitrary files from internal locations.\n(CVE-2026-34830)\n\nIt was discovered that Rack did not properly handle messages with Unicode.\nAn attacker could possibly use this issue to cause a denial of service.\n(CVE-2026-34831)\n\nIt was discovered that Rack did not properly parse the Host header. An\nattacker could possibly use this issue to bypass security filters or poison\ngenerated links. (CVE-2026-34835)","status":"published","published":"2026-11-03T17:12:03Z","modified":"2026-11-04T03:43:07.892494882Z","updated_at":"2026-11-04T03:56:18.279609Z"}]}}