{"id":"CVE-2026-81509","url":"https://www.cyber-defence.io/tools/cve/CVE-2026-81509","generatedAt":"2026-10-28T02:23:41.156Z","title":"nforwardauth is a forward auth service that allows the use of a single authentication middleware for multiple sites.","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.","published":"2026-10-26T18:18:46.000Z","lastModified":"2026-10-26T20:18:38.000Z","status":"Deferred","sourceIdentifier":"security-advisories@github.com","cvss":{"version":"3.1","score":6.1,"severity":"MEDIUM","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N"},"cwe":["CWE-601"],"affected":[],"epss":null,"kev":{"listed":false},"exploits":{"count":0,"verified":false,"firstPublished":null,"source":"Exploit-DB (https://gitlab.com/exploit-database/exploitdb)","entries":[]},"verdict":{"level":"low","text":"Lower severity and no EPSS score yet. Track it; it rarely justifies an emergency change on its own."},"changes":[{"kind":"new","label":"New CVE","at":"2026-10-26T18:18:46.000Z","detail":{"score":"6.1","severity":"MEDIUM","publishedAt":"2026-10-26T18:18:46.367Z"},"summary":"New CVE, medium severity (CVSS 6.1)."}],"references":[{"url":"https://github.com/nosduco/nforwardauth/commit/664f2602f9e1459558d1c4c55019f6d48bc64c43","source":"security-advisories@github.com"},{"url":"https://github.com/nosduco/nforwardauth/pull/71","source":"security-advisories@github.com"},{"url":"https://github.com/nosduco/nforwardauth/releases/tag/v1.5.1","source":"security-advisories@github.com"},{"url":"https://github.com/nosduco/nforwardauth/security/advisories/GHSA-q64r-v7j5-6hfg","source":"security-advisories@github.com"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-81509","epss":"https://www.first.org/epss/","kev":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog","exploitdb":"https://www.exploit-db.com/"},"licence":"CC BY 4.0 — link back to the CVE Explorer if you publish the results; upstream data remains subject to its own terms."}