CVE-2026-40596: 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...

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.

Metrics

CVSS 4.0

7.2/10

CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:P/VC:H/VI:L/VA:L/SC:H/SI:H/SA:L/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

EPSS Probability

0.42%

34.0th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-79

References

Timeline

Published: May 22, 2026
Last Modified: Jun 17, 2026
Status: Deferred

Frequently Asked Questions

What is CVE-2026-40596?

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.

How severe is CVE-2026-40596?

CVE-2026-40596 has a CVSS score of 7.2/10 (HIGH severity). The EPSS model estimates a 0.42% probability of exploitation in the next 30 days.

How do I fix CVE-2026-40596?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.