Cloudanix VulnDB

CVE-2026-33433

High · 8.8

CVSS

8.8

EPSS

0.6%

Published

Mar 27, 2026

CISA due date

—

The record

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 packages

Ecosystem Package Introduced Fixed
openSUSE:Leap 15.6 govulncheck-vulndb 0 0.0.20260402T184258-150000.1.158.1

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