CVE-2026-40596 — Vulnerability in mantisbt/mantisbt — CVE Details

HIGH

MantisBT is Vulnerable to XSS leading to account takeover via updating a user's font family preference

Published May 11, 2026Updated September 10, 2026Source: osv

Summary

Any authenticated user can inject arbitrary HTML via updating their account's font family. ### Impact Cross-site scripting. The injected payload will be reflected in every MantisBT page. Leveraging another vulnerability (CSP bypass, see [GHSA-9c3j-xm6v-j7j3](https://github.com/mantisbt/mantisbt/security/advisories/GHSA-9c3j-xm6v-j7j3)), the attacker could achieve account takeover. ### Patches - 9e8409cdd979eba86ef532756fc47c1d8112d22d ### Workarounds None ### Credits Thanks to siunam (Tang Cheuk Hei) for discovering and responsibly reporting the issue.

Advisory Timeline

First published May 11, 2026 (154 days ago).
Last revised September 10, 2026 — 121 days after initial publication.

Remediation

Upgrade to the fixed version using your package manager.

Composer

Update mantisbt/mantisbt to 2.28.2 or later

composer require "mantisbt/mantisbt:^2.28.2"

After upgrading, run your dependency scanner again to confirm the vulnerability is resolved.

Affected Packages (1)

Affects 1 ecosystem: packagist (1).

Package	Ecosystem	Affected	Fixed In
mantisbt/mantisbt	packagist	2.11.0, 2.11.1, 2.12.0, 2.12.1 (+53 more)	2.28.2

Vulnerability Classification

Common Weakness Enumeration (CWE) identifiers for this vulnerability type.

CWE-79
Cross-site Scripting (XSS)MITRE

CVSS Score Breakdown

What the CVSS (Common Vulnerability Scoring System) 8.6 score means for each attack dimension.

Attack Vector

Network

Attack Complexity

Low

Privileges Required

Low

User Interaction

Scope

—

Confidentiality

—

Integrity

—

Availability

—

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

References

Frequently Asked Questions

What is CVE-2026-40596?: MantisBT is Vulnerable to XSS leading to account takeover via updating a user's font family preference This vulnerability has been assigned a severity rating of HIGH (CVSS score: 8.6/10).
How do I check if my project is affected by CVE-2026-40596?: CVE-2026-40596 affects mantisbt/mantisbt. Use GeekWala's free vulnerability scanner to check your dependencies against CVE-2026-40596 and 200,000+ other known vulnerabilities.

Severity & Exploitability

CVSS Score

8.6

High exploitability or significant impact. Prioritize remediation within days.

Also Known As

GHSA-j3v9-553h-x28j

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