CVE-2026-40596: MantisBT is vulnerable to XSS and potential account takeover via user font family preference update

Severity: high (CVSS 7.2 v4.0)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.4% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-05-22 · updated 2026-07-23
Weakness: CWE-79

Description

Mantis Bug Tracker (MantisBT) is an open source issue tracker. Versions 2.11.0 through 2.28.1 allow any authenticated user to inject arbitrary HTML by updating their account's font family. Upon exploitation, an XSS payload would be reflected on every MantisBT page. Leveraging another vulnerability (CSP bypass, see GHSA-9c3j-xm6v-j7j3), the attacker could achieve account takeover. This issue has been fixed in version 2.28.2.

Affected products

mantisbt: from 2.11.0, < 2.28.2

References

https://github.com/mantisbt/mantisbt/commit/9e8409cdd979eba86ef532756fc47c1d8112d22d
https://github.com/mantisbt/mantisbt/security/advisories/GHSA-9c3j-xm6v-j7j3
https://github.com/mantisbt/mantisbt/security/advisories/GHSA-j3v9-553h-x28j
https://mantisbt.org/bugs/view.php?id=37011
https://mantisbt.org/bugs/view.php?id=37016

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