{"id":"CVE-2026-26962","aliases":["DEBIAN-CVE-2026-26962","EUVD-2026-18417","GHSA-rx22-g9mx-qrhv","SUSE-SU-2026:1745-1","SUSE-SU-2026:1964-1","SUSE-SU-2026:23321-1","SUSE-SU-2026:2487-1","UBUNTU-CVE-2026-26962","USN-8989-1","openSUSE-SU-2026:21640-1"],"status":"published","title":"Rack: Header injection in multipart requests","description":"Rack is a modular Ruby web server interface. From version 3.2.0 to before version 3.2.6, Rack::Multipart::Parser unfolds folded multipart part headers incorrectly. When a multipart header contains an obs-fold sequence, Rack preserves the embedded CRLF in parsed parameter values such as filename or name instead of removing the folded line break during unfolding. As a result, applications that later reuse those parsed values in HTTP response headers may be vulnerable to downstream header injection or response splitting. This issue has been patched in version 3.2.6.","severity":{"version":"3.1","score":4.8,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N","level":"medium","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-11","score":0.00235,"percentile":0.14655,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-93"],"published":"2026-04-02T17:10:17Z","modified":"2026-11-04T03:43:07Z","fixes":[{"ecosystem":"RubyGems","package":"rack","fixed_in":["3.2.6"],"sources":["ghsa","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: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":"3.2.0"},{"fixed":"3.2.6"}]}]},{"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":"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":"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"}]}],"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","1.5.2-3+deb8u3ubuntu1~esm11"]},{"source":"osv","ecosystem":"Ubuntu:Pro:16.04:LTS","package":"ruby-rack","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"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","1.6.4-3ubuntu0.2+esm10"]},{"source":"osv","ecosystem":"Ubuntu:Pro:18.04:LTS","package":"ruby-rack","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"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","1.6.4-4ubuntu0.2+esm10"]},{"source":"osv","ecosystem":"Ubuntu:Pro:20.04:LTS","package":"ruby-rack","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2.0.6-3","2.0.7-2","2.0.7-2ubuntu0.1","2.0.7-2ubuntu0.1+esm1","2.0.7-2ubuntu0.1+esm2","2.0.7-2ubuntu0.1+esm3","2.0.7-2ubuntu0.1+esm4","2.0.7-2ubuntu0.1+esm5","2.0.7-2ubuntu0.1+esm6","2.0.7-2ubuntu0.1+esm7","2.0.7-2ubuntu0.1+esm8","2.0.7-2ubuntu0.1+esm9","2.0.7-2ubuntu0.1+esm10"]},{"source":"osv","ecosystem":"Ubuntu:22.04:LTS","package":"ruby-rack","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2.1.4-3","2.1.4-4","2.1.4-5","2.1.4-5ubuntu1","2.1.4-5ubuntu1.1","2.1.4-5ubuntu1.2"]},{"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: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-rx22-g9mx-qrhv","tags":["x_refsource_CONFIRM","Mitigation","Vendor Advisory","advisory","web"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-26962","tags":["advisory"]},{"url":"https://github.com/rubysec/ruby-advisory-db/blob/master/gems/rack/CVE-2026-26962.yml","tags":["web"]},{"url":"https://github.com/advisories/GHSA-rx22-g9mx-qrhv"},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/26xxx/CVE-2026-26962.json","tags":["advisory"]},{"url":"https://security-tracker.debian.org/tracker/CVE-2026-26962","tags":["advisory"]},{"url":"https://github.com/rack/rack","tags":["package"]},{"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-2026-26962","tags":["report"]},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-26962","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-2026-32762","tags":["report"]},{"url":"https://ubuntu.com/security/CVE-2026-34230","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-2026-26962","title":"Rack: Header injection in multipart requests","description":"Rack is a modular Ruby web server interface. From version 3.2.0 to before version 3.2.6, Rack::Multipart::Parser unfolds folded multipart part headers incorrectly. When a multipart header contains an obs-fold sequence, Rack preserves the embedded CRLF in parsed parameter values such as filename or name instead of removing the folded line break during unfolding. As a result, applications that later reuse those parsed values in HTTP response headers may be vulnerable to downstream header injection or response splitting. This issue has been patched in version 3.2.6.","status":"published","published":"2026-04-02T17:10:17.091Z","modified":"2026-04-03T18:13:06.632Z","cvss":[{"version":"3.1","score":4.8,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N","level":"medium","assessor":"cna"}],"cwes":["CWE-93"],"updated_at":"2026-11-02T13:38:20.971157Z"}],"euvd":[{"id":"EUVD-2026-18417","description":"Rack is a modular Ruby web server interface. From version 3.2.0 to before version 3.2.6, Rack::Multipart::Parser unfolds folded multipart part headers incorrectly. When a multipart header contains an obs-fold sequence, Rack preserves the embedded CRLF in parsed parameter values such as filename or name instead of removing the folded line break during unfolding. As a result, applications that later reuse those parsed values in HTTP response headers may be vulnerable to downstream header injection or response splitting. This issue has been patched in version 3.2.6.","status":"published","published":"2026-04-02T17:10:17Z","modified":"2026-04-03T18:13:06Z","cvss":[{"version":"3.1","score":4.8,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N","level":"medium"}],"updated_at":"2026-11-02T19:25:16.550278Z"}],"ghsa":[{"id":"GHSA-rx22-g9mx-qrhv","title":"Rack's improper unfolding of folded multipart headers preserves CRLF in parsed parameter values","description":"## Summary\n\n`Rack::Multipart::Parser` unfolds folded multipart part headers incorrectly. When a multipart header contains an obs-fold sequence, Rack preserves the embedded CRLF in parsed parameter values such as `filename` or `name` instead of removing the folded line break during unfolding.\n\nAs a result, applications that later reuse those parsed values in HTTP response headers may be vulnerable to downstream header injection or response splitting.\n\n## Details\n\n`Rack::Multipart::Parser` accepts folded multipart header values and unfolds them during parsing. However, the unfolding behavior does not fully remove the embedded line break sequence from the parsed value.\n\nThis means a multipart part header such as:\n\n```http\nContent-Disposition: form-data; name=\"file\"; filename=\"test\\r\\n foo.txt\"\n```\n\ncan result in a parsed parameter value that still contains CRLF characters.\n\nThe issue is not that Rack creates a second multipart header field. Rather, the problem is that CRLF remains embedded in the parsed metadata value after unfolding. If an application later uses that value in a security-sensitive context, such as constructing an HTTP response header, the preserved CRLF may alter downstream header parsing.\n\nAffected values may include multipart parameters such as `filename`, `name`, or similar parsed header attributes.\n\n## Impact\n\nApplications that accept multipart form uploads may be affected if they later reuse parsed multipart metadata in HTTP headers or other header-sensitive contexts.\n\nIn affected deployments, an attacker may be able to supply a multipart parameter value containing folded line breaks and cause downstream header injection, response splitting, cache poisoning, or related response parsing issues.\n\nThe practical impact depends on application behavior. If parsed multipart metadata is not reused in HTTP headers, the issue may be limited to incorrect parsing behavior rather than a direct exploit path.\n\n## Mitigation\n\n* Update to a patched version of Rack that removes CRLF correctly when unfolding folded multipart header values.\n* Avoid copying upload metadata such as `filename` directly into HTTP response headers without sanitization.\n* Sanitize or reject carriage return and line feed characters in multipart-derived values before reusing them in response headers, logs, or downstream protocol contexts.\n* Where feasible, normalize uploaded filenames before storing or reflecting them.","status":"published","published":"2026-04-02T20:31:01Z","modified":"2026-05-13T16:17:38Z","cvss":[{"version":"3.1","score":4.8,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N","level":"medium"}],"cwes":["CWE-93"],"updated_at":"2026-11-02T14:40:08.003212Z"}],"nvd":[{"id":"CVE-2026-26962","description":"Rack is a modular Ruby web server interface. From version 3.2.0 to before version 3.2.6, Rack::Multipart::Parser unfolds folded multipart part headers incorrectly. When a multipart header contains an obs-fold sequence, Rack preserves the embedded CRLF in parsed parameter values such as filename or name instead of removing the folded line break during unfolding. As a result, applications that later reuse those parsed values in HTTP response headers may be vulnerable to downstream header injection or response splitting. This issue has been patched in version 3.2.6.","status":"published","published":"2026-04-02T18:16:26.773Z","modified":"2026-07-24T21:10:00.143Z","cvss":[{"version":"3.1","score":4.8,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N","level":"medium","assessor":"secondary"},{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N","level":"medium","assessor":"primary"}],"cwes":["CWE-93"],"updated_at":"2026-11-02T14:12:12.73929Z"}],"osv":[{"id":"CVE-2026-26962","title":"Rack: Header injection in multipart requests","description":"Rack is a modular Ruby web server interface. From version 3.2.0 to before version 3.2.6, Rack::Multipart::Parser unfolds folded multipart part headers incorrectly. When a multipart header contains an obs-fold sequence, Rack preserves the embedded CRLF in parsed parameter values such as filename or name instead of removing the folded line break during unfolding. As a result, applications that later reuse those parsed values in HTTP response headers may be vulnerable to downstream header injection or response splitting. This issue has been patched in version 3.2.6.","status":"published","published":"2026-04-02T17:10:17.091Z","modified":"2026-10-28T02:31:04.019484683Z","cvss":[{"version":"3.1","score":4.8,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N","level":"medium"}],"cwes":["CWE-93"],"updated_at":"2026-11-02T15:44:59.80315Z"},{"id":"DEBIAN-CVE-2026-26962","description":"Rack is a modular Ruby web server interface. From version 3.2.0 to before version 3.2.6, Rack::Multipart::Parser unfolds folded multipart part headers incorrectly. When a multipart header contains an obs-fold sequence, Rack preserves the embedded CRLF in parsed parameter values such as filename or name instead of removing the folded line break during unfolding. As a result, applications that later reuse those parsed values in HTTP response headers may be vulnerable to downstream header injection or response splitting. This issue has been patched in version 3.2.6.","status":"published","published":"2026-04-02T18:16:26.773Z","modified":"2026-10-01T03:03:00.843763598Z","cvss":[{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N","level":"medium"}],"updated_at":"2026-11-02T15:45:53.877573Z"},{"id":"GHSA-rx22-g9mx-qrhv","title":"Rack's improper unfolding of folded multipart headers preserves CRLF in parsed parameter values","description":"## Summary\n\n`Rack::Multipart::Parser` unfolds folded multipart part headers incorrectly. When a multipart header contains an obs-fold sequence, Rack preserves the embedded CRLF in parsed parameter values such as `filename` or `name` instead of removing the folded line break during unfolding.\n\nAs a result, applications that later reuse those parsed values in HTTP response headers may be vulnerable to downstream header injection or response splitting.\n\n## Details\n\n`Rack::Multipart::Parser` accepts folded multipart header values and unfolds them during parsing. However, the unfolding behavior does not fully remove the embedded line break sequence from the parsed value.\n\nThis means a multipart part header such as:\n\n```http\nContent-Disposition: form-data; name=\"file\"; filename=\"test\\r\\n foo.txt\"\n```\n\ncan result in a parsed parameter value that still contains CRLF characters.\n\nThe issue is not that Rack creates a second multipart header field. Rather, the problem is that CRLF remains embedded in the parsed metadata value after unfolding. If an application later uses that value in a security-sensitive context, such as constructing an HTTP response header, the preserved CRLF may alter downstream header parsing.\n\nAffected values may include multipart parameters such as `filename`, `name`, or similar parsed header attributes.\n\n## Impact\n\nApplications that accept multipart form uploads may be affected if they later reuse parsed multipart metadata in HTTP headers or other header-sensitive contexts.\n\nIn affected deployments, an attacker may be able to supply a multipart parameter value containing folded line breaks and cause downstream header injection, response splitting, cache poisoning, or related response parsing issues.\n\nThe practical impact depends on application behavior. If parsed multipart metadata is not reused in HTTP headers, the issue may be limited to incorrect parsing behavior rather than a direct exploit path.\n\n## Mitigation\n\n* Update to a patched version of Rack that removes CRLF correctly when unfolding folded multipart header values.\n* Avoid copying upload metadata such as `filename` directly into HTTP response headers without sanitization.\n* Sanitize or reject carriage return and line feed characters in multipart-derived values before reusing them in response headers, logs, or downstream protocol contexts.\n* Where feasible, normalize uploaded filenames before storing or reflecting them.","status":"published","published":"2026-04-02T20:31:01Z","modified":"2026-09-10T03:51:03.209768917Z","cvss":[{"version":"3.1","score":4.8,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N","level":"medium"}],"cwes":["CWE-93"],"updated_at":"2026-11-02T15:46:56.639206Z"},{"id":"UBUNTU-CVE-2026-26962","description":"Rack is a modular Ruby web server interface. From version 3.2.0 to before version 3.2.6, Rack::Multipart::Parser unfolds folded multipart part headers incorrectly. When a multipart header contains an obs-fold sequence, Rack preserves the embedded CRLF in parsed parameter values such as filename or name instead of removing the folded line break during unfolding. As a result, applications that later reuse those parsed values in HTTP response headers may be vulnerable to downstream header injection or response splitting. This issue has been patched in version 3.2.6.","status":"published","published":"2026-04-02T18:16:00Z","modified":"2026-11-04T03:42:04.581402365Z","cvss":[{"version":"3.1","score":4.8,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N","level":"medium"},{"version":"3.1","score":6.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N","level":"medium"}],"updated_at":"2026-11-04T03:56:18.279609Z"},{"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"}]}}