Traefik is an open source HTTP reverse proxy and load balancer. From 3.6.11 until 3.7.13, checkPassword in pkg/middlewares/auth/basic_auth.go constructs the BasicAuth singleflight key from the submitted password and stored secret. Concurrent requests for absent usernames therefore coalesce on one key while configured usernames perform separate password hashes, creating an unauthenticated timing discrepancy that reveals whether a username exists. Sequential checks remain cost-equalized, Traefik v2 and Digest authentication are not affected, and the issue does not disclose credentials or bypass authentication. This issue is fixed in version 3.7.13.
CVE-2026-88010
CVSS base score
5.3 (v3.1)
Severity
MEDIUM
Attack vector
Network
Weakness
CWE-208
Last modified
October 29, 2026
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
Affected products
traefik traefik
References
- github.com Patch
- github.com Issue Tracking, Patch
- github.com Release Notes
- github.com Vendor Advisory, Patch