CVE-2026-88007: Traefik

Critical severity, CVSS 9.1. EPSS: 0.6% chance of exploitation in the next 30 days.

Traefik is an open source HTTP reverse proxy and load balancer. From 2.11.0 until 2.11.57 and 3.7.13, the HTTP/3 entrypoint ConnContext does not call service.AddTransportOnContext, so kerberosRoundTripper uses a shared backend transport instead of a transport dedicated to each frontend connection. With HTTP/3 enabled, a backend using connection-bound NTLM or Negotiate authentication, and backend keep-alive, an unrelated client can reuse a backend connection authenticated for a victim, read victim-only data, and act as that victim without the victim credentials. This issue is fixed in 2.11.57 and 3.7.13.

Affected products

• Traefik Traefik: from 2.8.2, before 2.11.56 (fixed in 2.11.56); from 3.0.0, before 3.7.12 (fixed in 3.7.12)

Published 2026-09-10. Last modified 2026-09-14.