Description
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 client-connection slot not keyed by ServersTransport, so one service's TLS client configuration is reused for another service's backend. An unauthenticated client can arm the slot via a backend issuing an NTLM or Negotiate challenge, then reach another service on the same keep-alive connection, bypassing its root CAs, server name, and certificate verification.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| traefik | traefik | 2.11.0 – < 2.11.58, 3.0.0 – < 3.7.14 | 2.11.58 |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | traefik | 3.7.16-1.1 | openSUSE-SU-2026:12281-1 |
Wolfi
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Wolfi rolling | traefik-3.6 | No fix yet | — |
Advisories 1
- openSUSE-SU-2026:12281-1 traefik-3.7.16-1.1 on GA media SUSE / openSUSE Security Updates · Oct 27, 2026
References
- GitHub Security Advisory (GHSA-cw35-4q88-3rmp) vendor-advisory
- VulnCheck Advisory: Traefik before 2.11.58 and 3.7.14 TLS Config Bypass via NTLM/Kerberos Round Tripper third-party-advisory