Vulnerability Description
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 Score
LOW
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Traefik | Traefik | < 2.11.43 |
Related Weaknesses (CWE)
References
- https://github.com/traefik/traefik/releases/tag/v2.11.43ProductRelease Notes
- https://github.com/traefik/traefik/releases/tag/v3.6.14ProductRelease Notes
- https://github.com/traefik/traefik/releases/tag/v3.7.0-rc.2ProductRelease Notes
- https://github.com/traefik/traefik/security/advisories/GHSA-6x2q-h3cr-8j2hPatchVendor Advisory
FAQ
What is CVE-2026-41263?
CVE-2026-41263 is a vulnerability with a CVSS score of 3.7 (LOW). 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 att...
How severe is CVE-2026-41263?
CVE-2026-41263 has been rated LOW with a CVSS base score of 3.7/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-41263?
Check the references section above for vendor advisories and patch information. Affected products include: Traefik Traefik.