CVE-2026-23849

File Browser provides a file managing interface within a specified directory and can be used to upload, delete, preview, rename, and edit files. Prior to version 2.55.0, the JSONAuth. Auth function contains a logic flaw that allows unauthenticated attackers to enumerate valid usernames by measuring the response time of the /api/login endpoint. The vulnerability exists due to a "short-circuit" evaluation in the authentication logic. When a username is not found in the database, the function returns immediately. However, if the username does exist, the code proceeds to verify the password using bcrypt (users.CheckPwd), which is a computationally expensive operation designed to be slow. This difference in execution path creates a measurable timing discrepancy. Version 2.55.0 contains a patch for the issue.

• CWE-208
• CWE-203

• https://github.com/filebrowser/filebrowser/commit/24781badd413ee20333aba5cce1919d676e01889Patch
• https://github.com/filebrowser/filebrowser/security/advisories/GHSA-43mm-m3h2-3prcExploit, Vendor Advisory

Published

Jan 19, 2026

Last Modified

Jun 17, 2026

Status

Analyzed

• How Strix found a critical auth bypass in etcdStrix autonomously discovered a critical authentication bypass in etcd, later designated CVE-2026-33413.
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