CVE-2026-65600: Traefik before v2.11.52 Authentication Bypass via ReplacePathRegex
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 Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
Traefikto a version that resolves this vulnerability.Fixed in 2.11.52 - Upgrade
Upgrade
Traefikto a version that resolves this vulnerability.Fixed in 3.6.23 - Upgrade
Upgrade
Traefikto a version that resolves this vulnerability.Fixed in 3.7.7 - Compensating control
If you cannot upgrade immediately, change any Traefik ReplacePathRegex middleware configuration that uses a user-controlled capture group that can match without a mandatory path separator (e.g., regex "^/api(.*)" with replacement "/$1"). Adjust the regex/replacement so the resulting forwarded path is validated/forced to match the normalized protected route structure and cannot produce un-normalized paths like "/../admin".
Event History
Frequently Asked Questions
What is the severity of CVE-2026-65600?
CVE-2026-65600 has a high severity rating of 7.8 according to the CVSS scoring system.
What versions of Traefik are affected by CVE-2026-65600?
CVE-2026-65600 affects Traefik versions up to v2.11.51, v3.6.0 to v3.6.22, and v3.7.0 to v3.7.6.
How do I fix CVE-2026-65600?
To fix CVE-2026-65600, upgrade your Traefik installation to version v2.11.52 or later, or to a version higher than v3.7.6.
What type of vulnerability is CVE-2026-65600?
CVE-2026-65600 is classified as an authentication bypass vulnerability caused by path traversal in the ReplacePathRegex middleware.
What can an attacker do with CVE-2026-65600?
An attacker exploiting CVE-2026-65600 could bypass authentication controls, potentially allowing unauthorized access to sensitive resources.