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    CVE-2026-121966

    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.

    Published:Nov 4, 2026
    Last Modified:Nov 4, 2026
    EPS:Nov 4, 2026
    EPSS Score:
    CVSS Score:8.7

    Affected Products

    Vendor
    Traefik
    Product
    Traefik

    Exploits

    No exploit reference

    Related CVEs

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    CVE-2026-119572 (CVSS 7) — Traefik from 3.7.0-ea.1 before 3.7.15 contains an authentication bypass vulnerability in the Kubernetes Ingres…
    CVE-2026-114656 (CVSS 6.9) — Traefik before 2.11.58 and 3.7.13 contains an authentication bypass vulnerability that allows unauthenticated …
    CVE-2026-114642 (CVSS 7) — Traefik 2.11.0 before 2.11.58 and 3.0.0 before 3.7.14 stores its NTLM/Kerberos backend round tripper in a clie…
    CVE-2026-114641 (CVSS 6.3) — Traefik 2.11.x before 2.11.58 and 3.x before 3.7.14 contains a race condition in NTLM and Kerberos (Negotiate)…
    CVE-2026-114640 (CVSS 7) — Traefik from v3.7.0 before v3.7.14 contains an authentication bypass vulnerability in its Kubernetes Ingress-N…
    CVE-2026-114639 (CVSS 7) — Traefik 2.11.0 before 2.11.58 and 3.0.0 before 3.7.14 contains an authentication bypass because a first reques…
    CVE-2026-114638 (CVSS 7) — Traefik v3.7.0 before v3.7.14 contains an improper authentication vulnerability in the Kubernetes Ingress NGIN…
    CVE-2026-114637 (CVSS 7) — Traefik from v3.2.0 before v3.7.14 contains an authentication bypass vulnerability in the experimental FastPro…

    Common Vulnerability Scoring System

    Attack Vector
    Network
    Adjacent
    Local
    Physical
    Privileges Required
    None
    Low
    High
    User Interaction
    None
    Required
    Scope
    Unchanged
    Changed
    Confidentiality
    None
    Low
    High
    Integrity
    None
    Low
    High
    Availability
    None
    Low
    High