CVE-2026-33433

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.

CVSS

No CVSS.

References

Link	Resource
https://github.com/traefik/traefik/releases/tag/v2.11.42
https://github.com/traefik/traefik/releases/tag/v3.6.11
https://github.com/traefik/traefik/releases/tag/v3.7.0-ea.3
https://github.com/traefik/traefik/security/advisories/GHSA-qr99-7898-vr7c

Configurations

No configuration.

History

No history.

Information

Published : 2026-03-27 15:16

Updated : 2026-03-30 13:26

NVD link : CVE-2026-33433

Mitre link : CVE-2026-33433

CVE.ORG link : CVE-2026-33433

JSON object : View

Products Affected

No product.

CWE

CWE-290

Authentication Bypass by Spoofing

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