7.0 High

CVE-2026-121966 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.

CVSS 4.0 detail

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

Exploitable remotely over the network, without an account and without any user action; with no direct impact on the vulnerable system.

Attack vector: Network
Attack complexity: Low
Attack requirements: Present
Privileges required: None
Interaction: None
Confidentiality: None
Integrity: None
Availability: None
Confidentiality of other systems: High
Integrity of other systems: High
Availability of other systems: None

Affected products and versions

Product	Affected versions	Fixed in
traefik 3.7	earliest → < 3.7.16	3.7.16
traefik 3.0	3.0.0 → < 3.7.16	3.7.16

References

GitHub Security Advisory (GHSA-hrpp-p4fc-wwf8) github.com
VulnCheck Advisory: Traefik before 2.11.60 and 3.7.16 ForwardAuth NTLM/Negotiate Identity Leak www.vulncheck.com

Timeline

Published November 4, 2026
Last modified November 4, 2026

The 80 CVEs of traefik →

CVE-2026-119574 Traefik from 3.2.0 before 3.7.15 contains a data race in the experimental FastProxy that allows unauthenticated… 8.2 High CVE-2026-119573 Traefik 3.7.11 before 3.7.15 contains an authorization bypass in the Kubernetes Ingress NGINX provider that skips the… 2.1 Low CVE-2026-119572 Traefik 3.7.0-ea.1 before 3.7.15 mTLS Bypass via Ingress NGINX Provider 7.0 High CVE-2026-114656 Traefik before 2.11.58 and 3.7.13 mTLS Bypass via Negated Host Matcher 6.9 Medium

Track this CVE