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OpenAdvisories
High · 7.6 CVE-2026-40597 EUVD-2026-31496GHSA-9c3j-xm6v-j7j3

MantisBT has a Content Security Policy bypass via attachments

Published May 22, 2026 · Updated May 26, 2026 · Assigned by GitHub_M

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 products

VendorProductAffectedFixed
mantisbt mantisbt < 2.28.2 —

Affected packages

EcosystemPackageAffectedFixedRecord
Packagist mantisbt/mantisbt < 2.28.2 2.28.2 GHSA-9c3j-xm6v-j7j3

References