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.
What this means
- Exposure
- Exploitable remotely over the network, without authentication and with no action from the victim.
- Impact
- An attacker can read sensitive data and modify or destroy data. The impact spreads beyond the vulnerable component into other parts of the system.
- Weakness
- Authentication relies on a spoofable value such as an IP address or header.
- Likelihood
- Its EPSS score stays low: nothing points to imminent exploitation, which is no reason to leave it unpatched.
What to doPatch without waiting for the next scheduled cycle. Start with the instances exposed to the internet.
Read automatically from the CVSS vector, the weakness type (CWE) and the EPSS score. The technical description above remains the one published by NIST.