CVE-2026-39960
MantisBT is Vulnerable to Stored XSS through Custom Field Textarea Values
Description
Mantis Bug Tracker (MantisBT) is an open source issue tracker. Versions 2.28.1 and below contain flawed logic that causes improper escaping of a textarea custom field's contents in the Update Issue page, (bug_update_page.php) allowing an attacker to inject HTML and, if CSP settings permit, execute arbitrary JavaScript when the page is loaded. This facilitates session theft, leading to admin account takeover, full project data access. In order to exploit this issue, a textarea-type custom field must be configured for the project, the attack must be carried out by an authenticated user with bug report permission (low privilege). This can affect any user viewing the bug edit form, including administrators. The issue has been fixed in version 2.28.2. If users cannot immediately upgrade, they can work around the issue by using the default Content-Security Policy, which blocks script execution.
INFO
Published Date :
May 20, 2026, 10:16 p.m.
Last Modified :
July 23, 2026, 3:10 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 3.1 | MEDIUM | [email protected] | ||||
| CVSS 3.1 | MEDIUM | MITRE-CVE |
Solution
- Upgrade MantisBT to version 2.28.2.
- If upgrade is not possible, use default CSP settings.
- Ensure custom fields are properly configured.
- Review user permissions regularly.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-39960.
| URL | Resource |
|---|---|
| https://github.com/mantisbt/mantisbt/commit/5fec0f448b7a7d7d539a6adb6dccceac4e4e4ab7 | |
| https://github.com/mantisbt/mantisbt/security/advisories/GHSA-qj6w-v29q-4rgx |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-39960 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-39960
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-39960 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-39960 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
CVE Translated by [email protected]
Jul. 23, 2026
Action Type Old Value New Value Added Translation Title: Mantis Bug Tracker (MantisBT), Description: Mantis Bug Tracker (MantisBT) es un rastreador de problemas de código abierto. Las versiones 2.28.1 e inferiores contienen lógica defectuosa que causa un escape incorrecto del contenido de un campo personalizado de tipo textarea en la página de Actualización de Incidencias (bug_update_page.PHP), permitiendo a un atacante inyectar HTML y, si la configuración de CSP lo permite, ejecutar JavaScript arbitrario cuando se carga la página. Esto facilita el robo de sesión, lo que lleva a la toma de control de la cuenta de administrador y acceso total a los datos del proyecto. Para explotar este problema, debe configurarse un campo personalizado de tipo textarea para el proyecto, y el ataque debe ser llevado a cabo por un usuario autenticado con permiso para informar errores (privilegio bajo). Esto puede afectar a cualquier usuario que vea el formulario de edición de errores, incluidos los administradores. El problema ha sido solucionado en la versión 2.28.2. Si los usuarios no pueden actualizar inmediatamente, pueden solucionar el problema utilizando la Política de Seguridad de Contenido predeterminada, que bloquea la ejecución de scripts. -
CVE Modified by [email protected]
Jun. 17, 2026
Action Type Old Value New Value Added Affected [{'vendor': 'mantisbt', 'product': 'mantisbt', 'versions': [{'status': 'affected', 'version': '< 2.28.2'}]}] -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Jun. 17, 2026
Action Type Old Value New Value Added SSVC {'id': 'CVE-2026-39960', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'no'}, {'technicalImpact': 'partial'}], 'version': '2.0.3', 'timestamp': '2026-05-21T13:29:35.775357Z'} -
New CVE Received by [email protected]
May. 20, 2026
Action Type Old Value New Value Added Description Mantis Bug Tracker (MantisBT) is an open source issue tracker. Versions 2.28.1 and below contain flawed logic that causes improper escaping of a textarea custom field's contents in the Update Issue page, (bug_update_page.php) allowing an attacker to inject HTML and, if CSP settings permit, execute arbitrary JavaScript when the page is loaded. This facilitates session theft, leading to admin account takeover, full project data access. In order to exploit this issue, a textarea-type custom field must be configured for the project, the attack must be carried out by an authenticated user with bug report permission (low privilege). This can affect any user viewing the bug edit form, including administrators. The issue has been fixed in version 2.28.2. If users cannot immediately upgrade, they can work around the issue by using the default Content-Security Policy, which blocks script execution. Added CVSS V3.1 AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N Added CWE CWE-79 Added Reference https://github.com/mantisbt/mantisbt/commit/5fec0f448b7a7d7d539a6adb6dccceac4e4e4ab7 Added Reference https://github.com/mantisbt/mantisbt/security/advisories/GHSA-qj6w-v29q-4rgx