How severe is CVE-2026-40596?

CVE-2026-40596 has a CVSS 4.0 base score of 7.2, rated high severity.

Is CVE-2026-40596 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (34th percentile), an estimate of the probability of exploitation in the next 30 days.

How do I fix CVE-2026-40596?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

Does CVE-2026-40596 have an EU (EUVD) identifier?

Yes. CVE-2026-40596 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-31492.

When was CVE-2026-40596 published?

CVE-2026-40596 was published on 2026-05-22 and last updated on 2026-06-17.

CVE-2026-40596

CVE-2026-40596 is a high-severity vulnerability with a CVSS 4.0 base score of 7.2. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-79.

Key facts

Severity: High (CVSS 4.0 base score 7.2)
EPSS exploit prediction: 0% (34th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-31492
Weakness: CWE-79
Published: 2026-05-22
Last modified: 2026-06-17

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.

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 4.0 base score of 7.2, rated high severity.
Is CVE-2026-40596 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (34th percentile), an estimate of the probability of exploitation in the next 30 days.
How do I fix CVE-2026-40596?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
Does CVE-2026-40596 have an EU (EUVD) identifier?: Yes. CVE-2026-40596 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-31492.
When was CVE-2026-40596 published?: CVE-2026-40596 was published on 2026-05-22 and last updated on 2026-06-17.

References

Other CWE-79 (Cross-site Scripting (XSS)) vulnerabilities

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CVE-2024-6886 — Critical (CVSS 10.0): Improper Neutralization of Input During Web Page Generation (XSS or 'Cross-site Scripting') vulnerability in Gitea…
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CVE-2023-45138 — Critical (CVSS 10.0): Change Request is an pplication allowing users to request changes on a wiki without publishing the changes directly.…
CVE-2022-4361 — Critical (CVSS 10.0): Keycloak, an open-source identity and access management solution, has a cross-site scripting (XSS) vulnerability in the…

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