{"id":"CVE-2026-81509","state":"PUBLISHED","title":"nforwardauth: Unvalidated r parameter allows post-authentication open redirect","description":"nforwardauth is a forward auth service that allows the use of a single authentication middleware for multiple sites. Versions prior to 1.5.1 accept an unvalidated `r` query parameter on the `/login` endpoint and use them as the post-authentication redirect destination. An unauthenticated attacker can create a legitimate `nforwardauth` login URL that redirects a victim to an attacker-controlled website after the victim successfully authenticates. This issue may facilitate phishing and other social-engineering attacks by abusing the trust associated with the legitimate authentication domain. This vulnerability does not provide an unauthenticated ForwardAuth bypass. Version 1.5.1 contains a patch.","publishedAt":"2026-10-26T17:19:15.467Z","updatedAt":"2026-10-26T19:34:58.155Z","severity":{"score":6.1,"label":"Medium","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N","source":"GitHub_M"},"assigner":"GitHub_M","products":["nosduco nforwardauth"],"affected":[{"vendor":"nosduco","product":"nforwardauth","versions":[{"version":"< 1.5.1","status":"affected"}]}],"references":["https://github.com/nosduco/nforwardauth/security/advisories/GHSA-q64r-v7j5-6hfg","https://github.com/nosduco/nforwardauth/pull/71","https://github.com/nosduco/nforwardauth/commit/664f2602f9e1459558d1c4c55019f6d48bc64c43","https://github.com/nosduco/nforwardauth/releases/tag/v1.5.1"],"weaknesses":["CWE-601"],"ingestedAt":"2026-10-29T20:13:15.269Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/81xxx/CVE-2026-81509.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-81509","state":"PUBLISHED","datePublished":"2026-10-26T17:19:15.467Z","dateUpdated":"2026-10-26T19:34:58.155Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-08-26T20:58:58.084Z"},"containers":{"cna":{"title":"nforwardauth: Unvalidated r parameter allows post-authentication open redirect","descriptions":[{"lang":"en","value":"nforwardauth is a forward auth service that allows the use of a single authentication middleware for multiple sites. Versions prior to 1.5.1 accept an unvalidated `r` query parameter on the `/login` endpoint and use them as the post-authentication redirect destination. An unauthenticated attacker can create a legitimate `nforwardauth` login URL that redirects a victim to an attacker-controlled website after the victim successfully authenticates. This issue may facilitate phishing and other social-engineering attacks by abusing the trust associated with the legitimate authentication domain. This vulnerability does not provide an unauthenticated ForwardAuth bypass. Version 1.5.1 contains a patch."}],"affected":[{"vendor":"nosduco","product":"nforwardauth","versions":[{"version":"< 1.5.1","status":"affected"}]}],"references":[{"url":"https://github.com/nosduco/nforwardauth/security/advisories/GHSA-q64r-v7j5-6hfg","name":"https://github.com/nosduco/nforwardauth/security/advisories/GHSA-q64r-v7j5-6hfg","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/nosduco/nforwardauth/pull/71","name":"https://github.com/nosduco/nforwardauth/pull/71","tags":["x_refsource_MISC"]},{"url":"https://github.com/nosduco/nforwardauth/commit/664f2602f9e1459558d1c4c55019f6d48bc64c43","name":"https://github.com/nosduco/nforwardauth/commit/664f2602f9e1459558d1c4c55019f6d48bc64c43","tags":["x_refsource_MISC"]},{"url":"https://github.com/nosduco/nforwardauth/releases/tag/v1.5.1","name":"https://github.com/nosduco/nforwardauth/releases/tag/v1.5.1","tags":["x_refsource_MISC"]}],"metrics":[{"cvssV3_1":{"attackComplexity":"LOW","attackVector":"NETWORK","availabilityImpact":"NONE","baseScore":6.1,"baseSeverity":"MEDIUM","confidentialityImpact":"LOW","integrityImpact":"LOW","privilegesRequired":"NONE","scope":"CHANGED","userInteraction":"REQUIRED","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N","version":"3.1"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-601","lang":"en","description":"CWE-601: URL Redirection to Untrusted Site ('Open Redirect')","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2026-10-26T18:12:30.433Z"},"source":{"advisory":"GHSA-q64r-v7j5-6hfg","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-10-26T19:29:40.719883Z","id":"CVE-2026-81509","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-10-26T19:34:58.155Z"}}]}}}