CVE-2026-33433

  1. OpenCVE
  2. Vulnerabilities (CVE)
  3. 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.

8.8 /10

CVSS v3 : HIGH

V3 Legend

Vector :

Exploitability : 2.8 / Impact : 5.9

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required LOW

User Interaction NONE

Confidentiality Impact HIGH

Integrity Impact HIGH

Availability Impact HIGH

Scope UNCHANGED

References
Link Resource
https://github.com/traefik/traefik/releases/tag/v2.11.42 Product Release Notes
https://github.com/traefik/traefik/releases/tag/v3.6.11 Product Release Notes
https://github.com/traefik/traefik/releases/tag/v3.7.0-ea.3 Product Release Notes
https://github.com/traefik/traefik/security/advisories/GHSA-qr99-7898-vr7c Exploit Patch Vendor Advisory
Configurations

Configuration 1 (hide)

OR cpe:2.3:a:traefik:traefik:*:*:*:*:*:*:*:*
cpe:2.3:a:traefik:traefik:*:*:*:*:*:*:*:*
cpe:2.3:a:traefik:traefik:3.7.0:ea1:*:*:*:*:*:*
cpe:2.3:a:traefik:traefik:3.7.0:ea2:*:*:*:*:*:*
History

03 Apr 2026, 17:09

Type Values Removed Values Added
References () https://github.com/traefik/traefik/releases/tag/v2.11.42 - () https://github.com/traefik/traefik/releases/tag/v2.11.42 - Product, Release Notes
References () https://github.com/traefik/traefik/releases/tag/v3.6.11 - () https://github.com/traefik/traefik/releases/tag/v3.6.11 - Product, Release Notes
References () https://github.com/traefik/traefik/releases/tag/v3.7.0-ea.3 - () https://github.com/traefik/traefik/releases/tag/v3.7.0-ea.3 - Product, Release Notes
References () https://github.com/traefik/traefik/security/advisories/GHSA-qr99-7898-vr7c - () https://github.com/traefik/traefik/security/advisories/GHSA-qr99-7898-vr7c - Exploit, Patch, Vendor Advisory
First Time Traefik
Traefik traefik
CPE cpe:2.3:a:traefik:traefik:3.7.0:ea2:*:*:*:*:*:*
cpe:2.3:a:traefik:traefik:*:*:*:*:*:*:*:*
cpe:2.3:a:traefik:traefik:3.7.0:ea1:*:*:*:*:*:*
CVSS v2 : unknown
v3 : unknown 		v2 : unknown
v3 : 8.8

27 Mar 2026, 15:16

Type Values Removed Values Added
New CVE
Information

Published : 2026-03-27 15:16

Updated : 2026-04-03 17:09

NVD link : CVE-2026-33433

Mitre link : CVE-2026-33433

CVE.ORG link : CVE-2026-33433

JSON object : View

Products Affected

traefik

  • traefik
CWE
CWE-290

Authentication Bypass by Spoofing