CVE-2026-65600: Traefik before v2.11.52 Authentication Bypass via ReplacePathRegex

Severity: medium (CVSS 5.3 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.6% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-07-22 · updated 2026-10-24
Weakness: CWE-22

Description

Traefik versions <= v2.11.51, >= v3.6.0 <= v3.6.22, and >= v3.7.0 <= v3.7.6 contain an authentication bypass via path traversal in the ReplacePathRegex middleware. When ReplacePathRegex is configured with a regex that captures user-controlled path segments without a mandatory path separator (e.g. regex "^/api(.*)", replacement "/$1"), the middleware forwards the replaced path to the backend without validating that it matches its normalized form. An unauthenticated remote attacker can send a crafted request (e.g. GET /api../admin) that produces an un-normalized path such as /../admin, which a backend that normalizes paths resolves to a protected route, bypassing authentication middleware. Fixed in v2.11.52, v3.6.23, and v3.7.7.

Affected products

Traefik: before 2.11.52; from 3.6.0 before 3.6.23; from 3.7.0 before 3.7.7 — fixed in 2.11.52, 3.6.23, 3.7.7

How to fix

Upgrade to a fixed version: Traefik 2.11.52, 3.6.23, 3.7.7. Check the vendor advisory for mitigations.

References

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