Vulnerability · Published Jul 6, 2026 · Assigned by GitHub_M

CVE-2026-54764ForwardAuth middleware leaks X-Forwarded-Port spoofing via untrusted X-Forwarded-Proto when trustForwardHeader=false

Medium 6.9

In plain English

A medium-severity insufficient verification of data authenticity in traefik from traefik. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 21% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 4.0)6.9Medium

Exploit odds (30 days)0.3%top 79.3% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official description

Traefik is an HTTP reverse proxy and load balancer. Prior to v2.11.51, v3.6.22, and v3.7.6, Traefik's ForwardAuth middleware, even when configured with trustForwardHeader: false, derives the X-Forwarded-Port header sent to the authentication service from the original incoming request instead of the sanitized forwarded request. As a result, an unauthenticated remote attacker can inject an X-Forwarded-Proto: https header over a plain HTTP connection and cause Traefik to forward X-Forwarded-Port: 443 to the authentication service, bypassing port-based authorization checks. This issue is fixed in versions v2.11.51, v3.6.22, and v3.7.6.

Affected packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
Go	github.com/traefik/traefik	no fix listed	GHSA-3q9r-p662-5j8m
Go	github.com/traefik/traefik	no fix listed	GO-2026-6202
Go	github.com/traefik/traefik/v2	2.11.51	GHSA-3q9r-p662-5j8m
Go	github.com/traefik/traefik/v2	2.11.51	GO-2026-6202
Go	github.com/traefik/traefik/v3	3.7.6	GHSA-3q9r-p662-5j8m
Go	github.com/traefik/traefik/v3	3.6.22, 3.7.6	GO-2026-6202
Go	github.com/traefik/traefik/v3	3.6.22	GHSA-3q9r-p662-5j8m

Affected products (as reported)

Vendor	Product	Versions
traefik	traefik	< 2.11.51>= 3.0.0, < 3.6.22>= 3.7.0, < 3.7.6

Weakness: CWE-345 · Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:N/SI:L/SA:N

References

https://github.com/traefik/traefik/security/advisories/GHSA-3q9r-p662-5j8m x_refsource_CONFIRM
https://github.com/traefik/traefik/pull/13344 x_refsource_MISC
https://github.com/traefik/traefik/commit/7ae92d8c2c10ac04ef5a03df0ed5019ce0f44b2d x_refsource_MISC