CVE-2026-41263

3.7 LOW
Published: April 30, 2026 Modified: May 01, 2026
View on NVD

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.

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CVSS v3.x Details

0.0 Low Medium High Critical 10.0
Vector String
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N

References to Advisories, Solutions, and Tools

Patch Vendor Advisory Exploit Third Party Advisory
https://github.com/traefik/traefik/releases/tag/v2.11.43
Source: security-advisories@github.com
Product Release Notes
https://github.com/traefik/traefik/releases/tag/v3.6.14
Source: security-advisories@github.com
Product Release Notes
https://github.com/traefik/traefik/releases/tag/v3.7.0-rc.2
Source: security-advisories@github.com
Product Release Notes
https://github.com/traefik/traefik/security/advisories/GHSA-6x2q-h3cr-8j2h
Source: security-advisories@github.com
Patch Vendor Advisory

4 reference(s) from NVD

Quick Stats

CVSS v3 Score
3.7 / 10.0
EPSS (Exploit Probability)
0.0%
2th percentile
Exploitation Status
Not in CISA KEV

Weaknesses (CWE)

Affected Vendors

traefik