Improper Escaping Vulnerability in Mantis Bug Tracker by MantisBT
CVE-2026-39960

5.4MEDIUM

Key Information:

Vendor

Mantisbt

Status
Mantisbt
Vendor
CVE Published:
20 May 2026

What is CVE-2026-39960?

Mantis Bug Tracker versions 2.28.1 and earlier suffer from a vulnerability due to flawed logic in handling textarea custom field inputs on the Update Issue page. This flaw allows attackers to inject malicious HTML and, under certain Content Security Policy (CSP) configurations, execute arbitrary JavaScript when the affected page is viewed. An attacker, who must be an authenticated user with permission to report bugs, can exploit this vulnerability to steal user sessions, potentially leading to unauthorized access to administrative accounts and sensitive project data. Users are advised to upgrade to version 2.28.2 to mitigate this risk. As a temporary measure, implementing the default CSP can help block script execution, reducing the chance of exploitation.

Affected Version(s)

mantisbt < 2.28.2

References

https://github.com/mantisbt/mantisbt/security/advisories/...
x_refsource_CONFIRM
https://github.com/mantisbt/mantisbt/commit/5fec0f448b7a7...
x_refsource_MISC

CVSS V3.1

Score:
5.4
Severity:
MEDIUM
Confidentiality:
Low
Integrity:
Low
Availability:
Low
Attack Vector:
Network
Attack Complexity:
Low
Privileges Required:
Low
User Interaction:
Required
Scope:
Changed

Timeline

  • Vulnerability published

  • Vulnerability Reserved

.