{"id":"CVE-2026-126083","state":"PUBLISHED","title":"Action Pack: Possible IP spoofing in Action Dispatch RemoteIp","description":"Action Pack is a framework for handling and responding to web requests. From 8.1 until 8.1.4.1, Since Rails 8.1.0, ActionDispatch::RemoteIp derives request.remote_ip from Rack::Request#forwarded_for, which under Rack 3 reads the RFC 7239 Forwarded header in preference to X-Forwarded-For. When a reverse proxy appends the client address to X-Forwarded-For but passes a client-supplied Forwarded header through unchanged, request.remote_ip returns an address chosen by the client, and the IP spoofing check does not raise, because it compares only Client-Ip with the forwarded addresses. An unauthenticated attacker could therefore spoof request.remote_ip, possibly bypassing IP-based access controls and rate limits keyed on the client address (including the default by: of rate_limit), and falsifying the client address in logs. An application is affected if it meets all of these requirements: Runs Rails 8.1.0 through 8.1.4 with Rack 3. Under Rack 2.2, forwarded_for reads only X-Forwarded-For. Is served behind a proxy that does not remove or overwrite a client-supplied Forwarded header. Relies on request.remote_ip for access control, rate limiting, or auditing. The fix detects a spoofed Forwarded header only when the proxy also sets X-Forwarded-For. An application whose proxy passes a client-supplied Forwarded header through and sets no X-Forwarded-For remains exposed after upgrading, and should configure the proxy to remove or overwrite Forwarded, or apply the workaround below. This issue is fixed in version 8.1.4.1.","publishedAt":"2026-11-10T21:09:33.682Z","updatedAt":"2026-11-10T21:09:33.682Z","severity":{"score":7.4,"label":"High","version":"3.0","vector":"CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N","source":"GitHub_M"},"assigner":"GitHub_M","products":["rails rails"],"affected":[{"vendor":"rails","product":"rails","versions":[{"version":">= 8.1, < 8.1.4.1","status":"affected"}]}],"references":["https://github.com/rails/rails/security/advisories/GHSA-2gff-2mmg-m73p","https://github.com/rails/rails/commit/2a01a5ac521184419d9a92fa2c25e102e68cd227","https://github.com/rails/rails/releases/tag/v8.1.4.1"],"weaknesses":["CWE-348"],"ingestedAt":"2026-11-10T21:16:04.848Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/126xxx/CVE-2026-126083.json","commit":"c5a01f083f4f1bb59d77be7743a509cc9f9b04ca","baselineCommit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-126083","state":"PUBLISHED","datePublished":"2026-11-10T21:09:33.682Z","dateUpdated":"2026-11-10T21:09:33.682Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-11-10T17:07:43.285Z"},"containers":{"cna":{"title":"Action Pack: Possible IP spoofing in Action Dispatch RemoteIp","descriptions":[{"lang":"en","value":"Action Pack is a framework for handling and responding to web requests. From 8.1 until 8.1.4.1, Since Rails 8.1.0, ActionDispatch::RemoteIp derives request.remote_ip from Rack::Request#forwarded_for, which under Rack 3 reads the RFC 7239 Forwarded header in preference to X-Forwarded-For. When a reverse proxy appends the client address to X-Forwarded-For but passes a client-supplied Forwarded header through unchanged, request.remote_ip returns an address chosen by the client, and the IP spoofing check does not raise, because it compares only Client-Ip with the forwarded addresses. An unauthenticated attacker could therefore spoof request.remote_ip, possibly bypassing IP-based access controls and rate limits keyed on the client address (including the default by: of rate_limit), and falsifying the client address in logs. An application is affected if it meets all of these requirements: Runs Rails 8.1.0 through 8.1.4 with Rack 3. Under Rack 2.2, forwarded_for reads only X-Forwarded-For. Is served behind a proxy that does not remove or overwrite a client-supplied Forwarded header. Relies on request.remote_ip for access control, rate limiting, or auditing. The fix detects a spoofed Forwarded header only when the proxy also sets X-Forwarded-For. An application whose proxy passes a client-supplied Forwarded header through and sets no X-Forwarded-For remains exposed after upgrading, and should configure the proxy to remove or overwrite Forwarded, or apply the workaround below. This issue is fixed in version 8.1.4.1."}],"affected":[{"vendor":"rails","product":"rails","versions":[{"version":">= 8.1, < 8.1.4.1","status":"affected"}]}],"references":[{"url":"https://github.com/rails/rails/security/advisories/GHSA-2gff-2mmg-m73p","name":"https://github.com/rails/rails/security/advisories/GHSA-2gff-2mmg-m73p","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/rails/rails/commit/2a01a5ac521184419d9a92fa2c25e102e68cd227","name":"https://github.com/rails/rails/commit/2a01a5ac521184419d9a92fa2c25e102e68cd227","tags":["x_refsource_MISC"]},{"url":"https://github.com/rails/rails/releases/tag/v8.1.4.1","name":"https://github.com/rails/rails/releases/tag/v8.1.4.1","tags":["x_refsource_MISC"]}],"metrics":[{"cvssV3_0":{"attackComplexity":"HIGH","attackVector":"NETWORK","availabilityImpact":"NONE","baseScore":7.4,"baseSeverity":"HIGH","confidentialityImpact":"HIGH","integrityImpact":"HIGH","privilegesRequired":"NONE","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N","version":"3.0"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-348","lang":"en","description":"CWE-348: Use of Less Trusted Source","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2026-11-10T21:09:33.682Z"},"source":{"advisory":"GHSA-2gff-2mmg-m73p","discovery":"UNKNOWN"}}}}}