File Browser vulnerable to Username Enumeration via Timing Attack in /api/login
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Impact type
- Information disclosure
- Confidentiality · integrity · availability
- Low · None · None
- Fix status
- Fixed
Attack profile from CVSS 3.1 · CNA. Fix status from CNA and GitHub. Impact type from CWE-208.
Summary
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.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- Yes
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| filebrowser | filebrowser | before 2.55.0 | 2.55.0 | Patch available | CNA |
| — | github.com/filebrowser/filebrowser (Go) | up to 1.11.0 | — | No fix listed | GHSA-43mm-m3h2-3prc |
| — | github.com/filebrowser/filebrowser/v2 (Go) | before 2.55.0 | 2.55.0 | Patch available | GHSA-43mm-m3h2-3prc |
- filebrowser Vendorfilebrowser Affected before 2.55.0 Fixed in 2.55.0 Patch available CNA
- github.com/filebrowser/filebrowser (Go) Vendor— Affected up to 1.11.0 Fixed in — No fix listed GHSA-43mm-m3h2-3prc
- github.com/filebrowser/filebrowser/v2 (Go) Vendor— Affected before 2.55.0 Fixed in 2.55.0 Patch available GHSA-43mm-m3h2-3prc
CPE configurations NVD · 1
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:filebrowser:filebrowser:*:*:*:*:*:*:*:* | before 2.55.0 | Vulnerable | filebrowser |
- cpe:2.3:a:filebrowser:filebrowser:*:*:*:*:*:*:*:* Versions before 2.55.0 Vulnerable ·filebrowser
Remediation
- Fix · CNA filebrowser (filebrowser) Fixed in 2.55.0
- Fix · GHSA-43mm-m3h2-3prc github.com/filebrowser/filebrowser/v2 (Go) Fixed in 2.55.0 Advisory →
Timeline
- 2026-10-02 Threatist record created from CVE-2026-23849
- 2026-10-03 Alias added: GHSA-43mm-m3h2-3prc
References
More Filebrowser vulnerabilities
- TI-2026-25251 File Browser Self Registration Grants Any User Admin Access When Default Permissions Include Admin CVSS 4.0CRITICAL 10.0
- TI-2026-23305 File Browser: TUS Delete Endpoint Bypasses Delete Permission Check CVSS 3.1CRITICAL 9.1
- TI-2026-26777 File Browser's Signup Grants Execution Permissions When Default Permissions Includes Execution CVSS 3.1CRITICAL 9.8
- TI-2025-33000 File Browser vulnerable to command execution allowlist bypass CVSS 3.1HIGH 8.1
- TI-2026-23759 FileBrowser Quantum: Stored XSS in public share page via unsanitized share metadata (text/template misuse) CVSS 3.1HIGH 8.9
- TI-2023-20699 A cross-site scripting (XSS) vulnerability in FileBrowser before v2.23.0 allows an… CVSS 3.1CRITICAL 9.0
Sources
- CVE-2026-23849 · CVE Program
- CVE-2026-23849 · NVD
- FIRST EPSS
- GHSA-43mm-m3h2-3prc · GitHub Advisory Database · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences