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CVE-2026-48020 traefik CVE debrief

Traefik, an HTTP reverse proxy and load balancer, has a high-severity vulnerability in its StripPrefix middleware. This vulnerability allows an unauthenticated attacker to bypass route-level authentication and authorization. The issue arises when a public router matches on a PathPrefix rule and applies the StripPrefix middleware. A request path containing .. or its percent-encoded form %2e%2e can match the public route at routing time. After the prefix is stripped and the path is normalized, it can resolve to a path served by a separate, authenticated router. Consequently, an attacker can reach protected backend paths, such as admin or internal configuration endpoints, without satisfying the authentication middleware attached to the protected router. The vulnerability is fixed in Traefik versions 2.11.48, 3.6.19, and 3.7.3.

Vendor
traefik
Product
Unknown
CVSS
HIGH 7.8
CISA KEV
Not listed in stored evidence
Original CVE published
2026-06-23
Original CVE updated
2026-06-26
Advisory published
2026-06-23
Advisory updated
2026-06-26

Who should care

Users of Traefik, particularly those who use the StripPrefix middleware in conjunction with route-level authentication and authorization, should be aware of this vulnerability. This includes administrators and developers who manage Traefik configurations and ensure the security of their HTTP reverse proxy and load balancer setups.

Technical summary

The vulnerability in Traefik's StripPrefix middleware can be exploited by an unauthenticated attacker to bypass route-level authentication and authorization. This is achieved by crafting a request path that can match a public route at routing time. After the prefix is stripped, the normalized path can resolve to a protected backend path served by a separate, authenticated router. The vulnerability has a CVSS score of 7.8 and is classified as HIGH severity. It affects Traefik versions prior to 2.11.48, 3.6.19, and 3.7.3.

Defensive priority

Given the high severity and potential impact of this vulnerability, defenders should prioritize patching Traefik instances to versions 2.11.48, 3.6.19, or 3.7.3 as soon as possible. Additionally, defenders should review their Traefik configurations to ensure that the StripPrefix middleware is not being used in a way that could be exploited.

Recommended defensive actions

  • Patch Traefik instances to versions 2.11.48, 3.6.19, or 3.7.3.
  • Review Traefik configurations to ensure secure use of the StripPrefix middleware.
  • Monitor for suspicious traffic that could indicate exploitation attempts.
  • Implement additional authentication and authorization checks for protected backend paths.
  • Consider compensating controls, such as Web Application Firewalls (WAFs), to detect and prevent exploitation.

Evidence notes

The vulnerability is documented in the official CVE record and the NVD detail page. The source item URL provides additional information from the NVD database. References to patches and mitigation strategies are available from the Traefik GitHub releases and security advisories.

Official resources

This article is AI-assisted and based on the supplied source corpus.