{"id":"CVE-2026-121966","title":"Traefik before 2.11.60 and 3.7.16 ForwardAuth NTLM/Negotiate Identity Leak","summary":"Traefik 2.x before 2.11.60 and 3.x before 3.7.16 sends ForwardAuth subrequests (and, in 3.7, Ingress NGINX auth-url requests) through an auth-server connection pool shared by all clients, exposing connection-bound NTLM or Negotiate authe…","severity":"high","cvss":8.7,"cvssVector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:N","cvssSource":"cna","cwe":["CWE-488"],"vendor":"traefik","product":"traefik","affected":["traefik < 2.11.60","traefik >= 3.0.0 < 3.7.16"],"ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"total","timestamp":"2026-11-04T18:13:59.569753Z"},"published":"2026-11-04","updated":"2026-11-04","sourceUpdated":"2026-11-04T18:17:29.572Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-121966","references":[{"url":"https://github.com/traefik/traefik/security/advisories/GHSA-hrpp-p4fc-wwf8","label":"GitHub Security Advisory (GHSA-hrpp-p4fc-wwf8)"},{"url":"https://www.vulncheck.com/advisories/traefik-before-2.11.60-and-3.7.16-forwardauth-ntlm-negotiate-identity-leak","label":"VulnCheck Advisory: Traefik before 2.11.60 and 3.7.16 ForwardAuth NTLM/Negotiate Identity Leak"}],"tags":["cve.org"],"ingestedAt":"2026-11-05T21:36:00.482Z","epss":0.00333,"epssPercentile":0.26838,"slug":"CVE-2026-121966","body":"## Overview\n\nTraefik 2.x before 2.11.60 and 3.x before 3.7.16 sends ForwardAuth subrequests (and, in 3.7, Ingress NGINX auth-url requests) through an auth-server connection pool shared by all clients, exposing connection-bound NTLM or Negotiate authentication. An unauthenticated attacker can reuse another user's authenticated connection, receiving the victim's identity via authResponseHeaders to access backends as that user.\n\n## Affected\n\n- `traefik < 2.11.60`\n- `traefik >= 3.0.0 < 3.7.16`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"twilight","depthScore":48,"depthScoreParts":{"impact":47.8,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}