🛡️ CVE-2026-33433
🟠 CVSS 8.8 — High ✅ No Known Exploit NVD
8.8
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

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.

Details

Severity High
CVSS Score 8.8
CVSS Vector CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CWE N/A
Public Exploit ✅ No
Source NVD
Published 2026-04-02
Updated 2026-06-15
Modified 2026-04-07

Affected Packages

Software From version Fixed in
github.com/traefik/traefik — —
github.com/traefik/traefik/v2 — —
github.com/traefik/traefik/v3 — —
traefik — —

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