CVE-2026-88011

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.

CVSS v3 8.1 HIGH

8.1^/10

CVSS v3 : HIGH

Vector :

Exploitability : 2.8 / Impact : 5.2

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required LOW

User Interaction NONE

Confidentiality Impact HIGH

Integrity Impact HIGH

Availability Impact NONE

Scope UNCHANGED

References

Link	Resource
https://github.com/traefik/traefik/commit/0331801c72329e0eaeb850e53ccce87c57fbecf8	Patch
https://github.com/traefik/traefik/pull/13720	Issue Tracking Patch
https://github.com/traefik/traefik/releases/tag/v2.11.56	Release Notes
https://github.com/traefik/traefik/releases/tag/v3.7.12	Release Notes
https://github.com/traefik/traefik/security/advisories/GHSA-rf44-j88r-hh8c	Patch Vendor Advisory

Configurations

Configuration 1 (hide)

OR	cpe:2.3:a:traefik:traefik::::::::
	cpe:2.3:a:traefik:traefik::::::::

History

No history.

Information

Published : 2026-09-10 16:18

Updated : 2026-09-15 15:17

NVD link : CVE-2026-88011

Mitre link : CVE-2026-88011

CVE.ORG link : CVE-2026-88011

JSON object : View

Products Affected

traefik

traefik

CWE

CWE-290

Authentication Bypass by Spoofing

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