A serious vulnerability was discovered in GitLab Community Edition (CE) and Enterprise Edition (EE), tracked as CVE-2025-0314. GitLab versions from 17.2 up to (but not including) 17.6.4, 17.7 up to 17.7.3, and 17.8 up to 17.8.1 are all affected by this vulnerability. The issue allows an attacker to exploit improper rendering of certain file types in order to launch Cross-Site Scripting (XSS) attacks.

Below, I break down the impact, show a simplified proof-of-concept, and point you to official references.

What Is the Vulnerability?

GitLab failed to properly sanitize user-supplied files of certain types (for example, .svg images or possibly .html and .md files). If you upload a malicious file to a GitLab repo, GitLab’s built-in file viewer might dangerously render embedded JavaScript code. When a victim views the affected file in GitLab’s web UI, the malicious script executes in the victim’s browser.

Victim views the file using the GitLab web interface on an unpatched server.

4. The malicious JavaScript runs in the victim’s browser, possibly stealing cookies or performing actions on behalf of the victim.

Example Malicious SVG (Proof of Concept)

<!-- Save as exploit.svg and upload to an affected GitLab instance -->
<svg xmlns="http://www.w3.org/200/svg"; onload="alert('XSS in GitLab!')">
  <circle cx="50" cy="50" r="40" fill="red" />
</svg>

When a GitLab user views this SVG through their browser, the onload handler triggers and displays an alert—proof that arbitrary JavaScript can run. In a real attack, the payload could easily steal cookies, local storage, or forge requests (for example using fetch or XMLHttpRequest).

Which Versions Are Affected?

- GitLab CE/EE 17.2. and later, up to 17.6.3
- GitLab CE/EE 17.7. up to 17.7.2
- GitLab CE/EE 17.8.

NOT affected:

17.8.1 (or later)

If you cannot upgrade, block uploads of suspicious file types like .svg or .html using GitLab’s file policies, and monitor for any unexpected behavior. Also consider disabling or restricting access to file rendering features.

Original References

- GitLab Security Advisory – CVE-2025-0314
- CVE Details – CVE-2025-0314
- GitLab blog: How XSS Can Be Exploited via SVG files
- OWASP XSS Cheat Sheet

Impact & Real-World Example

Imagine you’re a developer. You’re reviewing your teammate’s new PR in GitLab and open a recent SVG diagram. Unknown to you, it contains JavaScript that makes a background request to an attacker’s server with your GitLab session cookie. Now, the attacker can potentially hijack your account and push malicious code or view confidential projects.

Conclusion

CVE-2025-0314 is a serious XSS vulnerability in GitLab. It can lead to account takeover, project leaks, or worse. Patch your GitLab urgently. If you manage a GitLab instance, double-check your version and enforce safe file policies. If you're a developer, be cautious when viewing files from untrusted sources.

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Timeline

Published on: 01/24/2025 03:15:07 UTC