CVE-2026-41263
CVE-2026-41263 · Traefik: BasicAuth middleware: timing side-channel vulnerability
This page contains facts from public vulnerability sources. Check the original advisory before updating.
Traefik is an HTTP reverse proxy and load balancer. Prior to versions 2.11.43, 3.6.14, and 3.7.0-rc.2, there is a timing side-channel vulnerability in Traefik's BasicAuth middleware that allows an attacker to enumerate valid usernames through response-time differences. The variable intended to hold a constant-time fallback secret always resolves to an empty string, causing the constant-time comparison to short-circuit in microseconds rather than performing a full bcrypt evaluation. This restores the original timing oracle and makes it possible to distinguish existing users from non-existing ones by measuring authentication response times. This issue has been patched in versions 2.11.43, 3.6.14, and 3.7.0-rc.2.
CVSS 6.3 · Medium · EPSS 0.4%
- Published
- Updated
Stack: web
Affected products and versions
traefik
- Versions
- < 2.11.43: Affected
- >= 3.0.0-beta1, < 3.6.14: Affected
- >= 3.7.0-ea.1, < 3.7.0-rc.2: Affected
No fix published