Vulnerability in Traefik
CVE-2026-54763
Traefik is an HTTP reverse proxy and load balancer. Prior to v2.11.51, v3.6.22, and v3.7.6, Traefik's BasicAuth, DigestAuth, and ForwardAuth middlewares strip canonical-cased spoofed identity headers before writing Traefik's own value, but do not account for underscore-variant header names, which many backends normalize identically to dashed forms. An attacker able to reach a protected route can inject an underscore-variant header that survives Traefik's stripping and reaches the backend alongside, or on the unauthenticated ForwardAuth authResponseHeaders path instead of, the value Traefik intended to set, spoofing identity or authorization context. This issue is fixed in versions v2.11.51, v3.6.22, and v3.7.6.
Published · last modified .
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.
EPSS exploit prediction
EPSS: 0.002 (13.7th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 14th percentile — 13.7% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.002 · newest: 0.002 · change: +0.000
Affected products
- Traefik — versions < 2.11.51, >= 3.0.0-beta1, < v3.6.22, >= 3.0.0-beta1, < 3.6.22
Weakness classification (CWE)
References
- github.com/traefik/traefik/commit/108a5264473a2cbc8f12d6d691a3c6553cdf2c1b (Patch)
- github.com/traefik/traefik/pull/13262 (Issue Tracking)
- github.com/traefik/traefik/security/advisories/GHSA-x677-9fxg-v5c5 (Patch, Vendor Advisory)
Frequently asked questions
- What is CVE-2026-54763?
- CVE-2026-54763 is a critical-severity vulnerability in Traefik, classified under Improper Handling of Case Sensitivity. CVSS score: 10.0/10. Published 2026-07-06.
- How severe is CVE-2026-54763?
- Critical severity. CVSS v3 base score is 10.0 out of 10.