Path Traversal in Traefik

CVE-2026-48020

Traefik is an HTTP reverse proxy and load balancer. Prior to 2.11.48, 3.6.19, and 3.7.3, there is a high severity vulnerability in Traefik's StripPrefix middleware that allows an unauthenticated attacker to bypass route-level authentication and authorization. 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 and then, after the prefix is stripped and the path is normalized, resolve to a path served by a separate, authenticated router. As a result, an attacker can reach protected backend paths — such as admin or internal configuration endpoints — without satisfying the authentication middleware attached to the protected router. This vulnerability is fixed in 2.11.48, 3.6.19, and 3.7.3.

EPSS: 0.008 (53.8th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 10.0 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:N.

Affected products

  • Traefik — versions >= 3.7.0-ea.1, < 3.7.3, >= 3.0.0-beta1, < 3.6.19, < 2.11.48

Weakness classification (CWE)

Public proof-of-concept exploits

References

Frequently asked questions

What is CVE-2026-48020?
CVE-2026-48020 is a critical-severity vulnerability in Traefik, classified under Authentication Bypass Using an Alternate Path or Channel. CVSS score: 10.0/10. Published 2026-06-23.
How severe is CVE-2026-48020?
Critical severity. CVSS v3 base score is 10.0 out of 10.
Is CVE-2026-48020 known to be exploited?
1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.