Is CVE-2026-39960 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-39960 being exploited in the wild.

How severe is CVE-2026-39960?

Medium severity, with a CVSS score of 5.4, published 20 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-2026-39960?

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-2026-39960 attacked?

It is attacked over the network, in a network appliance.

Am I affected by CVE-2026-39960?

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.

CVE-2026-39960: MantisBT stored XSS in textarea custom fields

Q: Is there a fix for CVE-2026-39960?

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.

Q: How is CVE-2026-39960 attacked?

It is attacked over the network, in a network appliance.

Q: Am I affected by CVE-2026-39960?

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.

CVE-2026-39960 · Severity: medium · CVSS 5.4 · Published 2026-05-20

MantisBT, a popular open-source bug tracking system, is vulnerable to a security flaw where malicious code can be hidden within custom text fields. If an attacker with basic reporting privileges saves a specially crafted message, it could allow them to hijack the sessions of other users, including administrators, when they view the affected ticket. This could lead to unauthorized access to sensitive project data or full control over the tracking system.

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

Quick answers

Is CVE-2026-39960 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-39960 being exploited in the wild.
How severe is CVE-2026-39960?: Medium severity, with a CVSS score of 5.4, published 20 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-2026-39960?: 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-2026-39960 attacked?: It is attacked over the network, in a network appliance.
Am I affected by CVE-2026-39960?: 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 due to improper escaping of textarea-type custom field contents in the Update Issue page (bug_update_page.php). An authenticated attacker with low-level bug reporting permissions can inject malicious HTML or JavaScript into these fields. When an administrator or another user views the bug edit form, the payload executes in their browser context. This can result in session hijacking and full project data access. The vulnerability is mitigated by default Content-Security Policy (CSP) settings, but remains exploitable if CSP is disabled or insufficiently restrictive. A fix is available in version 2.28.2.

Affected products

MantisBT MantisBT <= 2.28.1

Identifiers

CVE-2026-39960
GHSA-qj6w-v29q-4rgx

Timeline

2026-05-09: disclosed
2026-05-11: advisory: GitHub Advisory published
2026-05-20: advisory: NVD published

References

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