CVE-2026-33433
HIGHTraefik Vulnerable to BasicAuth/DigestAuth Identity Spoofing via Non-Canonical headerField
Title source: cnaDescription
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.
References (4)
Scores
CVSS v3
8.8
EPSS
0.0002
EPSS Percentile
6.4%
Attack Vector
NETWORK
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CISA SSVC
Vulnrichment
Exploitation
none
Automatable
no
Technical Impact
partial
Details
CWE
CWE-290
Status
published
Products (6)
traefik/traefik
3.7.0 ea1 (2 CPE variants)
traefik/traefik
< 2.11.42 (2 CPE variants)
traefik/traefik
0 - 2.11.42Go
traefik/traefik
3.0.0-beta1 - 3.6.12Go
traefik/traefik
>= 3.0.0-beta1, < 3.6.11
traefik/traefik
>= 3.7.0-ea.1, < 3.7.0-ea.3
Published
Mar 27, 2026
Tracked Since
Mar 29, 2026