CVE-2026-34463 MantisBT has Stored HTML Injection/XSS via Clone Issue Form
Attackers with manager access can inject HTML into project names, leading to stored XSS when users clone issues from other projects.
- Exploited in the wild
- Not known
- Login needed
- An administrator
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-34463?
CVE-2026-34463 is a high-severity cross-site scripting vulnerability in mantisbt, published on 19 May 2026. An attacker needs administrator access to exploit it, with no action from the victim.
Official description
Mantis Bug Tracker (MantisBT) is an open source issue tracker. Versions 2.28.1 and prior contain a Stored XSS vulnerability. When cloning an issue originating from a Project other than the current one, the clone form (bug_report_page.php) prepends the source Project name before the category selector without proper escaping, allowing an attacker able to to inject HTML if they can set the Project's name (which typically requires manager or administrator access level). This issue has been resolved in version 2.28.2.
Weakness: CWE-79
Which versions are affected by CVE-2026-34463?
2 open source packages ship an affected version, including mantisbt/mantisbt.
| Package | Affected | Fixed in |
|---|---|---|
mantisbt/mantisbt Packagist | All versions | 2.28.2 |
mantisbt/mantisbt Packagist | All versions | 2.28.2 |
How do I fix CVE-2026-34463?
Upgrade mantisbt/mantisbt to 2.28.2 or later.
Escape output for the context it lands in and set a strict Content Security Policy. Upgrading the affected component is the real fix. More about Cross-site scripting.
Is CVE-2026-34463 being exploited?
There is no known exploitation of CVE-2026-34463 in the wild and no public exploit code.
Sources
Also known as GHSA-fvjf-68wh-rwp2.