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Vulnerability record · CVE-2026-71326 · published 6 August 2026

CVE-2026-71326: Traefik improper authentication vulnerability

Traefik · Traefik

Traefik 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.

2.1 CVSS 4.0 Low EPSS 0.34% · top 75.2% CWE-287 · Improper authentication
2.1CVSS 4.0 base score
0.34%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
5References
16 Sep 2026Last modified by NVD

Description

Traefik 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.

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:

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://github.com/traefik/traefik/commit/b5ace8eb5d6779980567f5e75efd2d9e08b7e350 Patch
https://github.com/traefik/traefik/pull/13572 Patch
https://github.com/traefik/traefik/releases/tag/v3.6.25 PatchRelease Notes
https://github.com/traefik/traefik/releases/tag/v3.7.10 PatchRelease Notes
https://github.com/traefik/traefik/security/advisories/GHSA-6765-c87h-8mrf PatchVendor Advisory

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Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2026-71326), CISA KEV, FIRST EPSS (scores of 2026-10-03). This page is refreshed as NVD updates the record.