{"id":"CVE-2026-32762","aliases":["DEBIAN-CVE-2026-32762","EUVD-2026-18423","GHSA-qfgr-crr9-7r49","MGASA-2026-0226","UBUNTU-CVE-2026-32762","USN-8989-1"],"status":"published","title":"Rack: Forwarded Header semicolon injection enables Host and Scheme spoofing","description":"Rack is a modular Ruby web server interface. From versions 3.0.0.beta1 to before 3.1.21 and 3.2.0 to before 3.2.6, Rack::Utils.forwarded_values parses the RFC 7239 Forwarded header by splitting on semicolons before handling quoted-string values. Because quoted values may legally contain semicolons, a header can be interpreted by Rack as multiple Forwarded directives rather than as a single quoted for value. In deployments where an upstream proxy, WAF, or intermediary validates or preserves quoted Forwarded values differently, this discrepancy can allow an attacker to smuggle host, proto, for, or by parameters through a single header value. This issue has been patched in versions 3.1.21 and 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":0.00186,"percentile":0.08253,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-436"],"published":"2026-04-02T17:06:50Z","modified":"2026-11-04T03:43:07Z","fixes":[{"ecosystem":"RubyGems","package":"rack","fixed_in":["3.1.21","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: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":"3.0.0.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: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":"3.0.0.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":"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}],"products":[{"vendor":"rack","product":"rack"}],"references":[{"url":"https://github.com/rack/rack/security/advisories/GHSA-qfgr-crr9-7r49","tags":["x_refsource_CONFIRM","Mitigation","Vendor Advisory","advisory","web","report"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-32762","tags":["advisory"]},{"url":"https://github.com/rubysec/ruby-advisory-db/blob/master/gems/rack/CVE-2026-32762.yml","tags":["web"]},{"url":"https://github.com/advisories/GHSA-qfgr-crr9-7r49"},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/32xxx/CVE-2026-32762.json","tags":["advisory"]},{"url":"https://security-tracker.debian.org/tracker/CVE-2026-32762","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-v569-hp3g-36wr","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://ubuntu.com/security/CVE-2026-32762","tags":["report"]},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-32762","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-2026-34230","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"]}],"sources":{"cve":[{"id":"CVE-2026-32762","title":"Rack: Forwarded Header semicolon injection enables Host and Scheme spoofing","description":"Rack is a modular Ruby web server interface. From versions 3.0.0.beta1 to before 3.1.21 and 3.2.0 to before 3.2.6, Rack::Utils.forwarded_values parses the RFC 7239 Forwarded header by splitting on semicolons before handling quoted-string values. Because quoted values may legally contain semicolons, a header can be interpreted by Rack as multiple Forwarded directives rather than as a single quoted for value. In deployments where an upstream proxy, WAF, or intermediary validates or preserves quoted Forwarded values differently, this discrepancy can allow an attacker to smuggle host, proto, for, or by parameters through a single header value. This issue has been patched in versions 3.1.21 and 3.2.6.","status":"published","published":"2026-04-02T17:06:50.819Z","modified":"2026-04-02T17:42:42.305Z","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-436"],"updated_at":"2026-11-02T14:19:57.100857Z"}],"euvd":[{"id":"EUVD-2026-18423","description":"Rack is a modular Ruby web server interface. From versions 3.0.0.beta1 to before 3.1.21 and 3.2.0 to before 3.2.6, Rack::Utils.forwarded_values parses the RFC 7239 Forwarded header by splitting on semicolons before handling quoted-string values. Because quoted values may legally contain semicolons, a header can be interpreted by Rack as multiple Forwarded directives rather than as a single quoted for value. In deployments where an upstream proxy, WAF, or intermediary validates or preserves quoted Forwarded values differently, this discrepancy can allow an attacker to smuggle host, proto, for, or by parameters through a single header value. This issue has been patched in versions 3.1.21 and 3.2.6.","status":"published","published":"2026-04-02T17:06:50Z","modified":"2026-04-02T17:42:42Z","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":"2026-11-02T19:25:22.606516Z"}],"ghsa":[{"id":"GHSA-qfgr-crr9-7r49","title":"Rack: Forwarded Header semicolon injection enables Host and Scheme spoofing","description":"## Summary\n\n`Rack::Utils.forwarded_values` parses the RFC 7239 `Forwarded` header by splitting on semicolons before handling quoted-string values. Because quoted values may legally contain semicolons, a header such as:\n\n```http\nForwarded: for=\"127.0.0.1;host=evil.com;proto=https\"\n```\n\ncan be interpreted by Rack as multiple `Forwarded` directives rather than as a single quoted `for` value.\n\nIn deployments where an upstream proxy, WAF, or intermediary validates or preserves quoted `Forwarded` values differently, this discrepancy can allow an attacker to smuggle `host`, `proto`, `for`, or `by` parameters through a single header value.\n\n## Details\n\n`Rack::Utils.forwarded_values` processes the header using logic equivalent to:\n\n```ruby\nforwarded_header.split(';').each_with_object({}) do |field, values|\n  field.split(',').each do |pair|\n    pair = pair.split('=').map(\u0026:strip).join('=')\n    return nil unless pair =~ /\\A(by|for|host|proto)=\"?([^\"]+)\"?\\Z/i\n    (values[$1.downcase.to_sym] ||= []) \u003c\u003c $2\n  end\nend\n```\n\nThe method splits on `;` before it parses individual `name=value` pairs. This is inconsistent with RFC 7239, which permits quoted-string values, and quoted strings may contain semicolons as literal content.\n\nAs a result, a header value such as:\n\n```http\nForwarded: for=\"127.0.0.1;host=evil.com;proto=https\"\n```\n\nis not treated as a single `for` value. Instead, Rack may interpret it as if the client had supplied separate `for`, `host`, and `proto` directives.\n\nThis creates an interpretation conflict when another component in front of Rack treats the quoted value as valid literal content, while Rack reparses it as multiple forwarding parameters.\n\n## Impact\n\nApplications that rely on `Forwarded` to derive request metadata may observe attacker-controlled values for `host`, `proto`, `for`, or related URL components.\n\nIn affected deployments, this can lead to host or scheme spoofing in derived values such as `req.host`, `req.scheme`, `req.base_url`, or `req.url`. Applications that use those values for password reset links, redirects, absolute URL generation, logging, IP-based decisions, or backend requests may be vulnerable to downstream security impact.\n\nThe practical security impact depends on deployment architecture. If clients can already supply arbitrary trusted `Forwarded` parameters directly, this bug may not add meaningful attacker capability. The issue is most relevant where an upstream component and Rack interpret the same `Forwarded` header differently.\n\n## Mitigation\n\n* Update to a patched version of Rack that parses `Forwarded` quoted-string values before splitting on parameter delimiters.\n* Avoid trusting client-supplied `Forwarded` headers unless they are normalized or regenerated by a trusted reverse proxy.\n* Prefer stripping inbound `Forwarded` headers at the edge and reconstructing them from trusted proxy metadata.\n* Avoid using `req.host`, `req.scheme`, `req.base_url`, or `req.url` for security-sensitive operations unless the forwarding chain is explicitly trusted and validated.","status":"published","published":"2026-04-02T20:31:52Z","modified":"2026-05-13T16:17:53Z","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-436"],"updated_at":"2026-11-02T14:40:08.003212Z"}],"nvd":[{"id":"CVE-2026-32762","description":"Rack is a modular Ruby web server interface. From versions 3.0.0.beta1 to before 3.1.21 and 3.2.0 to before 3.2.6, Rack::Utils.forwarded_values parses the RFC 7239 Forwarded header by splitting on semicolons before handling quoted-string values. Because quoted values may legally contain semicolons, a header can be interpreted by Rack as multiple Forwarded directives rather than as a single quoted for value. In deployments where an upstream proxy, WAF, or intermediary validates or preserves quoted Forwarded values differently, this discrepancy can allow an attacker to smuggle host, proto, for, or by parameters through a single header value. This issue has been patched in versions 3.1.21 and 3.2.6.","status":"published","published":"2026-04-02T18:16:27.73Z","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-436"],"updated_at":"2026-11-02T14:12:12.73929Z"}],"osv":[{"id":"CVE-2026-32762","title":"Rack: Forwarded Header semicolon injection enables Host and Scheme spoofing","description":"Rack is a modular Ruby web server interface. From versions 3.0.0.beta1 to before 3.1.21 and 3.2.0 to before 3.2.6, Rack::Utils.forwarded_values parses the RFC 7239 Forwarded header by splitting on semicolons before handling quoted-string values. Because quoted values may legally contain semicolons, a header can be interpreted by Rack as multiple Forwarded directives rather than as a single quoted for value. In deployments where an upstream proxy, WAF, or intermediary validates or preserves quoted Forwarded values differently, this discrepancy can allow an attacker to smuggle host, proto, for, or by parameters through a single header value. This issue has been patched in versions 3.1.21 and 3.2.6.","status":"published","published":"2026-04-02T17:06:50.819Z","modified":"2026-10-28T02:30:46.332559287Z","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-436"],"updated_at":"2026-11-02T15:45:01.548715Z"},{"id":"DEBIAN-CVE-2026-32762","description":"Rack is a modular Ruby web server interface. From versions 3.0.0.beta1 to before 3.1.21 and 3.2.0 to before 3.2.6, Rack::Utils.forwarded_values parses the RFC 7239 Forwarded header by splitting on semicolons before handling quoted-string values. Because quoted values may legally contain semicolons, a header can be interpreted by Rack as multiple Forwarded directives rather than as a single quoted for value. In deployments where an upstream proxy, WAF, or intermediary validates or preserves quoted Forwarded values differently, this discrepancy can allow an attacker to smuggle host, proto, for, or by parameters through a single header value. This issue has been patched in versions 3.1.21 and 3.2.6.","status":"published","published":"2026-04-02T18:16:27.73Z","modified":"2026-10-01T03:03:21.929358877Z","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":"2026-11-02T15:45:54.232518Z"},{"id":"GHSA-qfgr-crr9-7r49","title":"Rack: Forwarded Header semicolon injection enables Host and Scheme spoofing","description":"## Summary\n\n`Rack::Utils.forwarded_values` parses the RFC 7239 `Forwarded` header by splitting on semicolons before handling quoted-string values. Because quoted values may legally contain semicolons, a header such as:\n\n```http\nForwarded: for=\"127.0.0.1;host=evil.com;proto=https\"\n```\n\ncan be interpreted by Rack as multiple `Forwarded` directives rather than as a single quoted `for` value.\n\nIn deployments where an upstream proxy, WAF, or intermediary validates or preserves quoted `Forwarded` values differently, this discrepancy can allow an attacker to smuggle `host`, `proto`, `for`, or `by` parameters through a single header value.\n\n## Details\n\n`Rack::Utils.forwarded_values` processes the header using logic equivalent to:\n\n```ruby\nforwarded_header.split(';').each_with_object({}) do |field, values|\n  field.split(',').each do |pair|\n    pair = pair.split('=').map(\u0026:strip).join('=')\n    return nil unless pair =~ /\\A(by|for|host|proto)=\"?([^\"]+)\"?\\Z/i\n    (values[$1.downcase.to_sym] ||= []) \u003c\u003c $2\n  end\nend\n```\n\nThe method splits on `;` before it parses individual `name=value` pairs. This is inconsistent with RFC 7239, which permits quoted-string values, and quoted strings may contain semicolons as literal content.\n\nAs a result, a header value such as:\n\n```http\nForwarded: for=\"127.0.0.1;host=evil.com;proto=https\"\n```\n\nis not treated as a single `for` value. Instead, Rack may interpret it as if the client had supplied separate `for`, `host`, and `proto` directives.\n\nThis creates an interpretation conflict when another component in front of Rack treats the quoted value as valid literal content, while Rack reparses it as multiple forwarding parameters.\n\n## Impact\n\nApplications that rely on `Forwarded` to derive request metadata may observe attacker-controlled values for `host`, `proto`, `for`, or related URL components.\n\nIn affected deployments, this can lead to host or scheme spoofing in derived values such as `req.host`, `req.scheme`, `req.base_url`, or `req.url`. Applications that use those values for password reset links, redirects, absolute URL generation, logging, IP-based decisions, or backend requests may be vulnerable to downstream security impact.\n\nThe practical security impact depends on deployment architecture. If clients can already supply arbitrary trusted `Forwarded` parameters directly, this bug may not add meaningful attacker capability. The issue is most relevant where an upstream component and Rack interpret the same `Forwarded` header differently.\n\n## Mitigation\n\n* Update to a patched version of Rack that parses `Forwarded` quoted-string values before splitting on parameter delimiters.\n* Avoid trusting client-supplied `Forwarded` headers unless they are normalized or regenerated by a trusted reverse proxy.\n* Prefer stripping inbound `Forwarded` headers at the edge and reconstructing them from trusted proxy metadata.\n* Avoid using `req.host`, `req.scheme`, `req.base_url`, or `req.url` for security-sensitive operations unless the forwarding chain is explicitly trusted and validated.","status":"published","published":"2026-04-02T20:31:52Z","modified":"2026-09-10T03:51:02.890606631Z","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-436"],"updated_at":"2026-11-02T15:46:54.40888Z"},{"id":"UBUNTU-CVE-2026-32762","description":"Rack is a modular Ruby web server interface. From versions 3.0.0.beta1 to before 3.1.21 and 3.2.0 to before 3.2.6, Rack::Utils.forwarded_values parses the RFC 7239 Forwarded header by splitting on semicolons before handling quoted-string values. Because quoted values may legally contain semicolons, a header can be interpreted by Rack as multiple Forwarded directives rather than as a single quoted for value. In deployments where an upstream proxy, WAF, or intermediary validates or preserves quoted Forwarded values differently, this discrepancy can allow an attacker to smuggle host, proto, for, or by parameters through a single header value. This issue has been patched in versions 3.1.21 and 3.2.6.","status":"published","published":"2026-04-02T18:16:00Z","modified":"2026-11-04T03:42:04.933438918Z","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":"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":"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"}]}}