Traefik: BasicAuth singleflight key collision allows authenticated identity spoofing

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-71326
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-08-06 22:18:29 UTC
Updated2026-08-06 22:18:29 UTC
DescriptionTraefik is an open source HTTP reverse proxy and load balancer. From 3.6.11 until 3.6.25 and 3.7.10, Traefik's BasicAuth middleware in pkg/middlewares/auth/basic_auth.go deduplicates concurrent password checks with a singleflight key built from the delimiter-free concatenation of password and secret, allowing an attacker who has a valid credential and the stored hash to authenticate as an unconfigured username when headerField trusts the forwarded identity. This issue is fixed in 3.6.25 and 3.7.10.

Risk And Classification

Primary CVSS: v4.0 2.1 LOW from [email protected]

CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/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-287 | CWE-287 CWE-287: Improper Authentication

VersionSourceTypeScoreSeverityVector
4.0[email protected]Secondary2.1LOWCVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/C...
4.0CNADECLARED2.1LOWCVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N

CVSS v4.0 Breakdown

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

CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/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 >= 3.6.11, < 3.6.25 Not specified
CNA Traefik Traefik affected >= 3.7.0, < 3.7.10 Not specified

References

ReferenceSourceLinkTags
github.com/traefik/traefik/pull/13572 [email protected] github.com
github.com/traefik/traefik/releases/tag/v3.6.25 [email protected] github.com
github.com/traefik/traefik/releases/tag/v3.7.10 [email protected] github.com
github.com/traefik/traefik/commit/b5ace8eb5d6779980567f5e75efd2d9e08b7e350 [email protected] github.com
github.com/traefik/traefik/security/advisories/GHSA-6765-c87h-8mrf [email protected] github.com
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