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GHSA-mmpx-jh39-wrv6

MediumCVSS 5.4 / 10
Published May 7, 2026·Last modified May 7, 2026
Affected Components(0)

No affected components available

Description

Summary

FileBrowser Quantum serves inline SVG files without a Content-Security-Policy header, allowing embedded JavaScript in SVG files to execute when accessed via public share links.

Verified on v1.3.0-stable.

Affected product

  • Product: FileBrowser Quantum (gtsteffaniak/filebrowser)
  • Verified version: v1.3.0-stable
  • Docker image: gtstef/filebrowser:latest
  • Affected endpoint: GET /public/api/resources/download?hash=HASH&inline=true
  • CWE: CWE-79 — Cross-site Scripting (Stored)

Impact

  • Stored XSS — Malicious SVG persists and executes for every visitor to the share link
  • No authentication required to trigger — Public share links are accessible to anyone
  • Session hijacking — If authenticated users click the link, their session can be stolen
  • Phishing — Attacker can redirect or overlay fake login forms

Reproduction

  1. Login as any user with upload permission
  2. Upload SVG file: 
    <svg xmlns="http://www.w3.org/2000/svg">
  <script>alert(document.domain)</script>
</svg>
  3. Create public share for the file
  4. Access the share link with ?inline=true
  5. JavaScript executes in browser

Root cause

The inline download endpoint returns SVG files with:

Content-Type: image/svg+xml
Content-Disposition: inline; filename="xss.svg"
X-Content-Type-Options: nosniff

But no CSP header to block script execution. The upstream project (filebrowser/filebrowser) mitigates this with:

Content-Security-Policy: script-src 'none'

Suggested fix

Add CSP header on inline file downloads:

w.Header().Set("Content-Security-Policy", "script-src 'none'")

This matches the upstream filebrowser/filebrowser implementation.

Risk Scores
Base Score
5.4

The vulnerability can be exploited over the network without needing physical access. It is easy for an attacker to exploit this vulnerability. An attacker needs basic access or low-level privileges. The attacker needs the user to perform some action, like clicking a link. The vulnerability can affect other systems as well, not just the initial system. There is a low impact on the confidentiality of the information. There is a low impact on the integrity of the data.

Threat Intelligence
5.0

Exploitation attempts have been detected. Elevated vigilance and prompt remediation are advised.

EPSS
N/A

Probability that this vulnerability will be exploited in the wild within the next 30 days.

Exploit
Not available

We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.

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Medium severity
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