CVE-2026-114656: Traefik before 2.11.58 and 3.7.13 mTLS Bypass via Negated Host Matcher

Severity: critical (CVSS 9.3 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-10-22 · updated 2026-10-30
Weakness: CWE-436

Description

Traefik before 2.11.58 and 3.7.13 contains an authentication bypass vulnerability that allows unauthenticated clients to skip client-certificate checks because negated Host matchers are counted as served domains. Attackers can reach backends protected by RequireAndVerifyClientCert when a router rule with !Host() creates a TLS options conflict that falls back to the default options.

Affected products

Traefik: before 2.11.58; from 3.0.0 before 3.7.13 — fixed in 2.11.58, 3.7.13
Traefik: before 2.11.58; from 3.0.0 before 3.7.13 — fixed in 2.11.58, 3.7.13

How to fix

Upgrade to a fixed version: Traefik 2.11.58, 3.7.13; Traefik 2.11.58, 3.7.13. Check the vendor advisory for mitigations.

References

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