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Vulnerability · Published May 22, 2026 · Assigned by GitHub_M

CVE-2026-40597MantisBT has a Content Security Policy bypass via attachments

High 7.6

In plain English

A high-severity cross-site scripting in mantisbt from mantisbt. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 43% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 4.0)7.6High
Exploit odds (30 days)0.5%top 57.1% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known

Official description

Mantis Bug Tracker (MantisBT) is an open source issue tracker. In versions 2.28.1 and below, given any pre-existing XSS / HTML injection vulnerability, an attacker can bypass the Content Security Policy's script-src directive by uploading a crafted attachment to any issue that, when accessed via the file_download.php link, will be downloaded with a valid JavaScript MIME type resulting in script execution. The uploaded payload must be sniffed as a valid JavaScript MIME type by PHP finfo (see file_create_finfo() API function). Non-JavaScript MIME types will not get imported in a <script> tag by the browser, due to response header X-Content-Type-Options being set to nosniff, which requires all imported JavaScript files to be a valid JavaScript MIME type. This issue has been fixed in version 2.28.2.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Packagistmantisbt/mantisbt2.28.2GHSA-9c3j-xm6v-j7j3

Affected products (as reported)

VendorProductVersions
mantisbt mantisbt < 2.28.2

Weakness: CWE-79, CWE-358 · Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:L/SC:N/SI:N/SA:N

References