filebrowser allows Stored Cross-Site Scripting through the Markdown preview function

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

7.6 · CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:L/A:N

EPSS

• CVE-2025-52902: 0.33% estimated exploitation activity in the next 30 days; percentile 26.79 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary

The Markdown preview function of File Browser v2.32.0 is vulnerable to Stored Cross-Site-Scripting (XSS). Any JavaScript code that is part of a Markdown file uploaded by a user will be executed by the browser Impact

A user can upload a malicious Markdown file to the application which can contain arbitrary HTML code. If another user within the same scope clicks on that file, a rendered preview is opened. JavaScript code that has been included will be executed. Malicious actions that are possible include: Obtaining a user's session token Elevating the attacker's privileges, if the victim is an administrator (e.g., gaining command execution rights) Vulnerability Description

Most Markdown parsers accept arbitrary HTML in a document and try rendering it accordingly. For instance, if one creates a file called xss.md with the following content: Bold and italic text will be rendered. Also, the renderer used in File Browser will try to display the image and execute the code…

Published by the source

27 Jun 2025, 15:01 UTC

Last modified by the source

4 Aug 2025, 20:33 UTC

Source last checked

26 Oct 2026, 15:10 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-4wx8-5gm2-2j97

Preview the exact text before you copy it. Commands are read-only suggestions; review them before running anything.

# Patch Next advisory brief: CVE-2025-52902

Advisory: filebrowser allows Stored Cross-Site Scripting through the Markdown preview function
IDs: CVE-2025-52902, GHSA-4wx8-5gm2-2j97
Record: https://patchnext.com/advisories/cve-2025-52902 (revision 1, source checked 26 Oct 2026, 15:10 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.6)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Partial vendor fix; fixed versions by package: github.com/filebrowser/filebrowser/v2 2.33.7. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/filebrowser/filebrowser/v2: affected < 2.33.7; fixed in 2.33.7
- Go github.com/filebrowser/filebrowser: affected <= 1.11.0

## Suggested inspection (read-only)
- Go github.com/filebrowser/filebrowser/v2: check the installed version with your package manager.
- Go github.com/filebrowser/filebrowser: check the installed version with your package manager.

## Supported action
No complete vendor fix is recorded. Follow the primary source's mitigation guidance and check this record again before closing anything.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/filebrowser/filebrowser/v2, github.com/filebrowser/filebrowser.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-4wx8-5gm2-2j97 (GitHub-reviewed advisory GHSA-4wx8-5gm2-2j97 lists affected ranges: Go github.com/filebrowser/filebrowser/v2 >=0 =0 <=1.11.0)

Commands are suggestions: review each one before running it.