MantisBT is Vulnerable to Stored XSS through Custom Field Textarea Values

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Summary

CVECVE-2026-39960
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-05-20 22:16:36 UTC
Updated2026-05-21 16:04:53 UTC
DescriptionMantis 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.

Risk And Classification

Primary CVSS: v3.1 5.4 MEDIUM from [email protected]

CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N

EPSS: 0.000330000 probability, percentile 0.100780000 (date 2026-05-27)

Problem Types: CWE-79 | CWE-79 CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary5.4MEDIUMCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
3.1CNADECLARED5.4MEDIUMCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
Low
User Interaction
Required
Scope
Changed
Confidentiality
Low
Integrity
Low
Availability
None

CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Mantisbt Mantisbt affected < 2.28.2 Not specified

References

ReferenceSourceLinkTags
github.com/mantisbt/mantisbt/security/advisories/GHSA-qj6w-v29q-4rgx [email protected] github.com
github.com/mantisbt/mantisbt/commit/5fec0f448b7a7d7d539a6adb6dccceac4e4e... [email protected] github.com
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