{"id":"CVE-2026-125109","state":"PUBLISHED","title":"Rack: Rack::Request#host_with_port (and #base_url / #url) return the raw invalid Host header — incomplete fix of CVE-2026-34835","description":"Rack is a modular Ruby web server interface. From 3.0 until 3.1.23 and 3.2.8, Rack::Request#host_with_port, #base_url, and #url can return an attacker-controlled invalid authority from Host, X-Forwarded-Host, or Forwarded: host= verbatim. Applications without an independent host allowlist that use these methods for absolute URLs, redirects, or origin-dependent checks can emit attacker-chosen delimiters, enabling redirect manipulation, string-based allowlist bypass, or unescaped markup reflection. Rails overrides these methods and is not expected to be affected. This issue is fixed in versions 3.1.23 and 3.2.8.","publishedAt":"2026-11-09T21:57:46.924Z","updatedAt":"2026-11-09T21:57:46.924Z","severity":{"score":4.8,"label":"Medium","version":"3.1","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N","source":"GitHub_M"},"assigner":"GitHub_M","products":["rack rack"],"affected":[{"vendor":"rack","product":"rack","versions":[{"version":">= 3.0, < 3.1.23","status":"affected"},{"version":">= 3.2, < 3.2.8","status":"affected"}]}],"references":["https://github.com/rack/rack/security/advisories/GHSA-2j8w-xcrc-x985","https://github.com/rack/rack/commit/4380381a56dc52556a436d6d794c8e18dc8b0565","https://github.com/rack/rack/commit/49386f460286b7346c7003b69a839de782cc8a39","https://github.com/rack/rack/releases/tag/v3.1.23","https://github.com/rack/rack/releases/tag/v3.2.8"],"weaknesses":["CWE-1286"],"ingestedAt":"2026-11-09T22:04:05.922Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/125xxx/CVE-2026-125109.json","commit":"9075bf95c24cae38173da5ec87797c6e02814bfe","baselineCommit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-125109","state":"PUBLISHED","datePublished":"2026-11-09T21:57:46.924Z","dateUpdated":"2026-11-09T21:57:46.924Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-11-09T17:45:35.935Z"},"containers":{"cna":{"title":"Rack: Rack::Request#host_with_port (and #base_url / #url) return the raw invalid Host header — incomplete fix of CVE-2026-34835","descriptions":[{"lang":"en","value":"Rack is a modular Ruby web server interface. From 3.0 until 3.1.23 and 3.2.8, Rack::Request#host_with_port, #base_url, and #url can return an attacker-controlled invalid authority from Host, X-Forwarded-Host, or Forwarded: host= verbatim. Applications without an independent host allowlist that use these methods for absolute URLs, redirects, or origin-dependent checks can emit attacker-chosen delimiters, enabling redirect manipulation, string-based allowlist bypass, or unescaped markup reflection. Rails overrides these methods and is not expected to be affected. This issue is fixed in versions 3.1.23 and 3.2.8."}],"affected":[{"vendor":"rack","product":"rack","versions":[{"version":">= 3.0, < 3.1.23","status":"affected"},{"version":">= 3.2, < 3.2.8","status":"affected"}]}],"references":[{"url":"https://github.com/rack/rack/security/advisories/GHSA-2j8w-xcrc-x985","name":"https://github.com/rack/rack/security/advisories/GHSA-2j8w-xcrc-x985","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/rack/rack/commit/4380381a56dc52556a436d6d794c8e18dc8b0565","name":"https://github.com/rack/rack/commit/4380381a56dc52556a436d6d794c8e18dc8b0565","tags":["x_refsource_MISC"]},{"url":"https://github.com/rack/rack/commit/49386f460286b7346c7003b69a839de782cc8a39","name":"https://github.com/rack/rack/commit/49386f460286b7346c7003b69a839de782cc8a39","tags":["x_refsource_MISC"]},{"url":"https://github.com/rack/rack/releases/tag/v3.1.23","name":"https://github.com/rack/rack/releases/tag/v3.1.23","tags":["x_refsource_MISC"]},{"url":"https://github.com/rack/rack/releases/tag/v3.2.8","name":"https://github.com/rack/rack/releases/tag/v3.2.8","tags":["x_refsource_MISC"]}],"metrics":[{"cvssV3_1":{"attackComplexity":"HIGH","attackVector":"NETWORK","availabilityImpact":"NONE","baseScore":4.8,"baseSeverity":"MEDIUM","confidentialityImpact":"LOW","integrityImpact":"LOW","privilegesRequired":"NONE","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N","version":"3.1"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-1286","lang":"en","description":"CWE-1286: Improper Validation of Syntactic Correctness of Input","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2026-11-09T21:57:46.924Z"},"source":{"advisory":"GHSA-2j8w-xcrc-x985","discovery":"UNKNOWN"}}}}}