CVEvulnerability

CVE-2026-88011

5.3 MEDIUM Published 2026-09-10 Modified 2026-09-15 Official page ↗
Status
Analyzed
Published
2026-09-10
Last modified
2026-09-15
Assigner
[email protected]
CVSS 4.0 ([email protected])
5.3 MEDIUM — CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
CVSS 3.1 ([email protected])
8.1 HIGH — CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N
Weaknesses
CWE-290

Description

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.

Affected configurations

• traefik traefik (< 2.11.56) • traefik traefik (>= 3.0.0 < 3.7.12)

Related

Weakness · CWE (1)

  • CWE-290 Authentication Bypass by Spoofing weakness

References