Vulnerability · Published Feb 21, 2026 · Assigned by GitHub_M
CVE-2026-27480Static Web Server: Timing-Based Username Enumeration in Basic Authentication
Medium 5.3
In plain English
A medium-severity security flaw in static-web-server from static-web-server. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 34% of all known vulnerabilities).
Official description
Static Web Server (SWS) is a production-ready web server suitable for static web files or assets. In versions 2.1.0 through 2.40.1, a timing-based username enumeration vulnerability in Basic Authentication allows attackers to identify valid users by exploiting early responses for invalid usernames, enabling targeted brute-force or credential-stuffing attacks. SWS checks whether a username exists before verifying the password, causing valid usernames to follow a slower code path (e.g., bcrypt hashing) while invalid usernames receive an immediate 401 response. This timing discrepancy allows attackers to enumerate valid accounts by measuring response-time differences. This issue has been fixed in version 2.41.0.
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| static-web-server | static-web-server | >= 2.1.0, < 2.41.0 |
Weakness: CWE-204 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N