{"affected":[{"product":"rack","source":"CNA: GitHub_M","vendor":"rack","versions":[{"status":"affected","version":">= 3.0, < 3.1.23"},{"status":"affected","version":">= 3.2, < 3.2.8"}]}],"cveId":"CVE-2026-125109","cwes":["CWE-1286"],"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.","epss":null,"exploits":[],"kev":null,"metrics":[{"score":4.8,"severity":"medium","source":"CNA: GitHub_M","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N","version":"3.1"}],"modifiedAt":1794261466924,"publishedAt":1794261466924,"references":[{"source":"CNA: GitHub_M","tags":["x_refsource_CONFIRM"],"url":"https://github.com/rack/rack/security/advisories/GHSA-2j8w-xcrc-x985"},{"source":"CNA: GitHub_M","tags":["x_refsource_MISC"],"url":"https://github.com/rack/rack/commit/4380381a56dc52556a436d6d794c8e18dc8b0565"},{"source":"CNA: GitHub_M","tags":["x_refsource_MISC"],"url":"https://github.com/rack/rack/commit/49386f460286b7346c7003b69a839de782cc8a39"},{"source":"CNA: GitHub_M","tags":["x_refsource_MISC"],"url":"https://github.com/rack/rack/releases/tag/v3.1.23"},{"source":"CNA: GitHub_M","tags":["x_refsource_MISC"],"url":"https://github.com/rack/rack/releases/tag/v3.2.8"}],"remediation":[],"revision":"6b0013c0d1201c27ee3631cc3bf20e5430ad1fe46cc4738aff111359a10a420c","sources":[{"modifiedAt":1794261466924,"name":"CNA: GitHub_M","retrievedAt":1794262186011,"url":"https://www.cve.org/CVERecord?id=CVE-2026-125109"}],"ssvc":null,"status":"published","title":"Rack: Rack::Request#host_with_port (and #base_url / #url) return the raw invalid Host header — incomplete fix of CVE-2026-34835","updatedAt":1794262186011}