Traefik is an open source HTTP reverse proxy and load balancer. Prior to 2.11.56, and from 3.0.0 until 3.7.12, a client-supplied dot-form header such as X.Authenticated.User survives ForwardAuth replacement and underscoreHeadersStrategy because Go treats it as distinct from X-Authenticated-User while normalization-prone CGI, WSGI, PHP, and NGINX backends collapse both names. A backend can consequently consume the client value instead of the identity Traefik asserted, allowing identity spoofing for any header managed by Traefik.
The aliasHeadersStrategy protection is disabled by default and must be configured as delete or reject. The mitigation is available in 2.11.56 and 3.7.12.
Attack Parameters
Attack Vector
Network
Can be exploited remotely
Attack Complexity
Low
Easy to exploit
Attack Requirements
Present
Additional conditions required
Privileges Required
Low
Basic privileges needed
User Interaction
None
No user interaction needed
Impact Assessment
Confidentiality
None
No data leak
Integrity
None
No data modification
Availability
None
No disruption
CVSS Vector v4.0
Weakness Type (CWE)
References 5
https://github.com/traefik/traefik/commit/0331801c72329e0eaeb850e53ccce87c57fbe…
security-advisories@github.com
https://github.com/traefik/traefik/pull/13720
security-advisories@github.com
https://github.com/traefik/traefik/releases/tag/v2.11.56
security-advisories@github.com
https://github.com/traefik/traefik/releases/tag/v3.7.12
security-advisories@github.com
https://github.com/traefik/traefik/security/advisories/GHSA-rf44-j88r-hh8c
security-advisories@github.com