CVEvulnerability

CVE-2026-33433

5.1 MEDIUM Published 2026-03-27 Modified 2026-07-15 Official page ↗
Status
Modified
Published
2026-03-27
Last modified
2026-07-15
Assigner
[email protected]
CVSS 4.0 ([email protected])
5.1 MEDIUM — CVSS:4.0/AV:N/AC:H/AT:P/PR:H/UI:N/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
CVSS 3.1 ([email protected])
8.8 HIGH — CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CVSS 3.1 (0b0ca135-0b70-47e7-9f44-1890c2a1c46c)
7.7 HIGH — CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:C/C:H/I:H/A:N
Weaknesses
CWE-290

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.

Affected configurations

• traefik traefik (< 2.11.42) • traefik traefik (>= 3.0.0 < 3.6.12) • traefik traefik 3.7.0

Related

Weakness · CWE (1)

  • CWE-290 Authentication Bypass by Spoofing weakness

References