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CVE-2026-54763

Traefik: headerField underscore-variant identity spoofing in BasicAuth / DigestAuth / ForwardAuth

Published: Jul 6, 2026Updated: Jul 8, 2026 Sources: CVE List NVDCWE-178
10.0CRITICAL
NVD MITRE
EPSS Score
0.2%
Top 89.1%
CISA KEV
Not in KEV
Exploits
No Known Exploits
Remediation
Patch Available
Self-Check
OpenVAS

Description

Traefik is an HTTP reverse proxy and load balancer. Prior to v2.11.51, v3.6.22, and v3.7.6, Traefik's BasicAuth, DigestAuth, and ForwardAuth middlewares strip canonical-cased spoofed identity headers before writing Traefik's own value, but do not account for underscore-variant header names, which many backends normalize identically to dashed forms. An attacker able to reach a protected route can inject an underscore-variant header that survives Traefik's stripping and reaches the backend alongside, or on the unauthenticated ForwardAuth authResponseHeaders path instead of, the value Traefik intended to set, spoofing identity or authorization context. This issue is fixed in versions v2.11.51, v3.6.22, and v3.7.6.

No summary for this CVE yet.

CVSS Vector Breakdown

AV:NAC:LPR:NUI:NS:CC:HI:HA:N
Exploitability
AV:NAttack Vector
Network
AC:LAttack Complexity
Low
PR:NPrivileges Required
None
UI:NUser Interaction
None
Scope
S:CScope
Changed
Impact
C:HConfidentiality
High
I:HIntegrity
High
A:NAvailability
None
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Weaknesses

CWE-178CWE-290CWE-345

Affected Products

traefik
oss-projectaka traefik enterprise
traefikOn-prem
Networking Infrastructure / load-balancer-proxy

Exploitability

Official Patch Available
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Attack Graph

Products CVE Techniques Tactics

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MITRE ATT&CK

2 techniques
Collection
Initial Access
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References

https://github.com/traefik/traefik/security/advisories/GHSA-x677-9fxg-v5c5
github.com
https://github.com/traefik/traefik/pull/13262
github.com
https://github.com/traefik/traefik/commit/108a5264473a2cbc8f12d6d691a3c6553cdf2c1b
github.com

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