{"id":"CVE-2026-121966","aliases":["EUVD-2026-116966","GHSA-6cm8-r9cr-2hc7","GHSA-hrpp-p4fc-wwf8"],"status":"published","title":"Traefik before 2.11.60 and 3.7.16 ForwardAuth NTLM/Negotiate Identity Leak","description":"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 authentication. An unauthenticated attacker can reuse another user's authenticated connection, receiving the victim's identity via authResponseHeaders to access backends as that user.","severity":{"version":"4.0","score":7,"vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N","level":"high","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-12","score":0.00333,"percentile":0.27042,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":false},"cwes":["CWE-488"],"published":"2026-11-04T15:33:28Z","modified":"2026-11-05T03:31:25Z","products":[{"vendor":"traefik","product":"traefik"}],"references":[{"url":"https://github.com/traefik/traefik/security/advisories/GHSA-hrpp-p4fc-wwf8","tags":["vendor-advisory","advisory"]},{"url":"https://www.vulncheck.com/advisories/traefik-before-2.11.60-and-3.7.16-forwardauth-ntlm-negotiate-identity-leak","tags":["third-party-advisory","advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-121966","tags":["advisory"]},{"url":"https://github.com/advisories/GHSA-6cm8-r9cr-2hc7"},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/121xxx/CVE-2026-121966.json","tags":["advisory"]}],"sources":{"cve":[{"id":"CVE-2026-121966","title":"Traefik before 2.11.60 and 3.7.16 ForwardAuth NTLM/Negotiate Identity Leak","description":"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 authentication. An unauthenticated attacker can reuse another user's authenticated connection, receiving the victim's identity via authResponseHeaders to access backends as that user.","status":"published","published":"2026-11-04T15:33:28.106Z","modified":"2026-11-04T18:17:29.572Z","cvss":[{"version":"4.0","score":7,"vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N","level":"high","assessor":"cna"},{"version":"3.1","score":8.7,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:N","level":"high","assessor":"cna"}],"cwes":["CWE-488"],"updated_at":"2026-11-04T19:37:11.952963Z"}],"euvd":[{"id":"EUVD-2026-116966","description":"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 authentication. An unauthenticated attacker can reuse another user's authenticated connection, receiving the victim's identity via authResponseHeaders to access backends as that user.","status":"published","published":"2026-11-04T15:33:28Z","modified":"2026-11-04T18:17:29Z","cvss":[{"version":"4.0","score":7,"vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N","level":"high"}],"updated_at":"2026-11-04T21:45:45.282595Z"}],"ghsa":[{"id":"GHSA-6cm8-r9cr-2hc7","title":"Traefik 2.x before 2.11.60 and 3.x before 3.7.16 sends ForwardAuth subrequests (and, in 3.7,...","description":"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 authentication. An unauthenticated attacker can reuse another user's authenticated connection, receiving the victim's identity via authResponseHeaders to access backends as that user.","status":"published","published":"2026-11-04T18:30:54Z","modified":"2026-11-04T18:31:01Z","cvss":[{"version":"4.0","score":7,"vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","level":"high"},{"version":"3.1","score":8.7,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:N","level":"high"}],"cwes":["CWE-488"],"updated_at":"2026-11-04T18:55:44.84967Z"}],"nvd":[{"id":"CVE-2026-121966","description":"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 authentication. An unauthenticated attacker can reuse another user's authenticated connection, receiving the victim's identity via authResponseHeaders to access backends as that user.","status":"published","published":"2026-11-04T16:17:50.107Z","modified":"2026-11-04T19:17:38.37Z","cvss":[{"version":"4.0","score":7,"vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","level":"high","assessor":"secondary"},{"version":"3.1","score":8.7,"vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:N","level":"high","assessor":"secondary"}],"cwes":["CWE-488"],"updated_at":"2026-11-04T21:42:34.71458Z"}],"osv":[{"id":"CVE-2026-121966","title":"Traefik before 2.11.60 and 3.7.16 ForwardAuth NTLM/Negotiate Identity Leak","description":"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 authentication. An unauthenticated attacker can reuse another user's authenticated connection, receiving the victim's identity via authResponseHeaders to access backends as that user.","status":"published","published":"2026-11-04T15:33:28.106Z","modified":"2026-11-05T21:16:09.776995165Z","cvss":[{"version":"4.0","score":7,"vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N","level":"high"}],"cwes":["CWE-488"],"updated_at":"2026-11-05T22:00:58.054534Z"}]}}