CVE Vulnerabilities

CVE-2026-88011

Authentication Bypass by Spoofing

Published: Sep 10, 2026 | Modified: Sep 15, 2026
CVSS 3.x
8.1
HIGH
Source:
NVD
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N
CVSS 2.x
RedHat/V2
RedHat/V3
Ubuntu
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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.

Weakness

This attack-focused weakness is caused by incorrectly implemented authentication schemes that are subject to spoofing attacks.

Affected Software

NameVendorStart VersionEnd Version
TraefikTraefik*2.11.56 (excluding)
TraefikTraefik3.0.0 (including)3.7.12 (excluding)

References