CVE-2026-41263
MEDIUM EPSS 28.7%
Published Apr 30, 20262mo ago · Modified Jun 17, 20262w ago
6.3 CVSS 4.0
Published Apr 30, 2026 2mo ago
Last Modified Jun 17, 2026 2w ago
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 Details
Base Score
Exploitability
Impact
Vector string
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/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:X/V:X/RE:X/U:X Attack Vector Network
Attack Complexity High
Privileges Required None
User Interaction None
Scope X
Threat Intelligence
EPSS Exploit Probability
28.7% percentile
Exploit & Patch Status
No Known Exploit
Patch Available
Weaknesses 1
CWE-208
Affected Products 6
References 4
- github.com https://github.com/traefik/traefik/releases/tag/v2.11.43
- github.com https://github.com/traefik/traefik/releases/tag/v3.6.14
- github.com https://github.com/traefik/traefik/releases/tag/v3.7.0-rc.2
- github.com https://github.com/traefik/traefik/security/advisories/GHSA-6x2q-h3cr-8j2h
Remediation
- github.com https://github.com/traefik/traefik/security/advisories/GHSA-6x2q-h3cr-8j2h