CVE-2026-41263
CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:L/SI:N/SA:N
Summary
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.
Affected Software
| Vendor | Product | Version Range | Status |
|---|---|---|---|
| traefik | traefik | < 2.11.43 | affected |
| traefik | traefik | >= 3.0.0-beta1, < 3.6.14 | affected |
| traefik | traefik | >= 3.7.0-ea.1, < 3.7.0-rc.2 | affected |
Weaknesses
- CWE-208: CWE-208: Observable Timing Discrepancy
ADP Enrichment
CISA ADP Vulnrichment
- SSVC:
- Exploitation: none
- Automatable: no
- Technical Impact: partial
References
- https://github.com/traefik/traefik/security/advisories/GHSA-6x2q-h3cr-8j2h
- https://github.com/traefik/traefik/releases/tag/v2.11.43
- https://github.com/traefik/traefik/releases/tag/v3.6.14
- https://github.com/traefik/traefik/releases/tag/v3.7.0-rc.2
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