CVE-2026-34463: MantisBT stored XSS in bug_report_page.php via project name

CVE-2026-34463 · Severity: high · CVSS 4 · Published 2026-05-19

MantisBT is a popular open-source bug tracking system. A security flaw in the issue cloning process allows users with administrative or manager privileges to inject malicious scripts into the platform by naming a project with malicious code. If exploited, this could allow an attacker to perform actions on behalf of other users or access sensitive data, though the impact is partially mitigated by modern browser security policies.

Technologies: MantisBT Mantis Bug Tracker, mantisbt/mantisbt (Packagist). Vendors: MantisBT, Packagist.

Quick answers

Is CVE-2026-34463 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-34463 being exploited in the wild.
How severe is CVE-2026-34463?
High severity, with a CVSS score of 4, published 19 May 2026.
Which products and versions are affected?
MantisBT Mantis Bug Tracker <= 2.28.1; MantisBT <= 2.28.1; mantisbt/mantisbt (Packagist) <= 2.28.1, ECOSYSTEM:introduced=0,fixed=2.28.2.
Is there a fix for CVE-2026-34463?
Yes. mantisbt/mantisbt (Packagist): upgrade to 2.28.2 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-34463 attacked?
It is attacked over the network, in a web application.
Am I affected by CVE-2026-34463?
Check whether you run MantisBT Mantis Bug Tracker, MantisBT or mantisbt/mantisbt (Packagist) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

  • mantisbt/mantisbt (Packagist): upgrade to 2.28.2 or later
    composer require mantisbt/mantisbt:^2.28.2

Technical details

A stored cross-site scripting (XSS) vulnerability exists in MantisBT's bug_report_page.php. When an issue is cloned from a different project, the source project's name is prepended to the category selector without adequate HTML escaping. An attacker with the ability to rename projects (typically requiring 'manager' or 'administrator' permissions) can inject arbitrary HTML/JavaScript. The vulnerability is triggered when a user views the clone issue form for an affected project. While a Content Security Policy (CSP) may restrict script execution, the underlying injection remains possible. The issue is fixed in version 2.28.2.

Affected products

  • MantisBT MantisBT <= 2.28.1

Identifiers

  • CVE-2026-34463
  • GHSA-fvjf-68wh-rwp2

Timeline

  • 2026-05-09: disclosed
  • 2026-05-11: advisory
  • 2026-05-19: other: NVD publication

References

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