CVE-2026-33433
Traefik Vulnerable to BasicAuth/DigestAuth Identity Spoofing via Non-Canonical headerField
CVSS Score
7.7
EPSS Score
0.0%
EPSS Percentile
0th
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.
| CWE | CWE-290 |
| Vendor | traefik |
| Product | traefik |
| Published | Mar 27, 2026 |
| Last Updated | Jul 15, 2026 |
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Affected Versions
traefik / traefik
< 2.11.42 >= 3.0.0-beta1, < 3.6.11 >= 3.7.0-ea.1, < 3.7.0-ea.3
References
github.com: https://github.com/traefik/traefik/security/advisories/GHSA-qr99-7898-vr7c github.com: https://github.com/traefik/traefik/releases/tag/v2.11.42 github.com: https://github.com/traefik/traefik/releases/tag/v3.6.11 github.com: https://github.com/traefik/traefik/releases/tag/v3.7.0-ea.3 access.redhat.com: https://access.redhat.com/security/cve/CVE-2026-33433 bugzilla.redhat.com: https://bugzilla.redhat.com/show_bug.cgi?id=2452289 security.access.redhat.com: https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-33433.json access.redhat.com: https://access.redhat.com/errata/RHSA-2026:10175