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

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Summary

CVECVE-2026-54764
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-07-06 21:16:56 UTC
Updated2026-07-07 15:16:48 UTC
DescriptionTraefik 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.

Risk And Classification

Primary CVSS: v4.0 6.9 MEDIUM from [email protected]

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/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

Problem Types: CWE-345 | CWE-345 CWE-345: Insufficient Verification of Data Authenticity

VersionSourceTypeScoreSeverityVector
4.0[email protected]Secondary6.9MEDIUMCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:N/SI:L/SA:N/E:X/C...
4.0CNADECLARED6.9MEDIUMCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:N/SI:L/SA:N

CVSS v4.0 Breakdown

Attack Vector
Network
Attack Complexity
Low
Attack Requirements
None
Privileges Required
None
User Interaction
None
Confidentiality
None
Integrity
None
Availability
None
Sub Conf.
None
Sub Integrity
Low
Sub Availability
None

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/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

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Traefik Traefik affected < 2.11.51 Not specified
CNA Traefik Traefik affected >= 3.0.0, < 3.6.22 Not specified
CNA Traefik Traefik affected >= 3.7.0, < 3.7.6 Not specified

References

ReferenceSourceLinkTags
github.com/traefik/traefik/pull/13344 [email protected] github.com
github.com/traefik/traefik/security/advisories/GHSA-3q9r-p662-5j8m [email protected] github.com
github.com/traefik/traefik/commit/7ae92d8c2c10ac04ef5a03df0ed5019ce0f44b2d [email protected] github.com
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