CVE-2026-114642: Traefik NTLM/Kerberos TLS configuration bypass

CVE-2026-114642 · Severity: high · CVSS 8.7 · Published 2026-10-22

Traefik is a reverse proxy and load balancer used to route and manage traffic to backend services. A vulnerability allows an unauthenticated attacker to bypass TLS security policies on backend connections by triggering NTLM or Kerberos authentication, then reusing that authenticated connection to reach other services with relaxed certificate verification. This could allow an attacker to intercept or manipulate traffic between the proxy and backend servers.

Technologies: Traefik. Vendors: Traefik.

Quick answers

Is CVE-2026-114642 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-114642 being exploited in the wild.
How severe is CVE-2026-114642?
High severity, with a CVSS score of 8.7, published 22 October 2026.
Which products and versions are affected?
Traefik 2.11.0 before 2.11.58; 3.0.0 before 3.7.14.
Is there a fix for CVE-2026-114642?
Yes: fixed in Traefik 2.11.58, 3.7.14. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-114642 attacked?
It is attacked over the network.
Am I affected by CVE-2026-114642?
Check whether you run Traefik at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

  • Fixed in: Traefik 2.11.58, 3.7.14

Technical details

The vulnerability exists in Traefik's NTLM/Kerberos backend authentication handling. When a backend issues an NTLM or Negotiate (Kerberos) challenge, Traefik caches the authenticated round tripper in a client-connection slot that is not keyed by ServersTransport, causing the first service's TLS configuration (root CAs, server name verification, client certificates) to be reused for subsequent requests to other services on the same HTTP keep-alive connection. An attacker can exploit this via network access without authentication by making an ordinary request to one service to arm the slot, then accessing another service on the same connection to bypass its TLS policies.

Affected products

  • Traefik Traefik 2.11.0 before 2.11.58; 3.0.0 before 3.7.14

Timeline

  • 2026-10-07: disclosed: GitHub Security Advisory published
  • 2026-10-22: advisory: NVD entry published

References

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