cvedb.io
CVE-2026-33433
HIGH · CVSS 8.8
EPSS exploitation probability: 0%
Published 2026-03-27T15:16:54.980 · Last modified 2026-06-30T03:18:40.357

Summary

Traefik is an HTTP reverse proxy and load balancer. Prior to versions 2.11.42, 3.6.11, and 3.7.0-ea.3, when `headerField` is configured with a non-canonical HTTP header name (e.g., `x-auth-user` instead of `X-Auth-User`), an authenticated attacker can inject their own canonical version of that header to impersonate any identity to the backend. The backend receives two header entries — the attacker-injected canonical one is read first, overriding Traefik's non-canonical write. Versions 2.11.42, 3.6.11, and 3.7.0-ea.3 patch the issue.

Affected products

traefik — traefik

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References

This product uses data from the NVD API but is not endorsed or certified by the NVD. Informational only; not professional security advice.