An issue was discovered in MantisBT before 2.24.3. Improper escaping of a custom field's name allows an attacker to inject HTML and, if CSP settings permit, achieve execution of arbitrary JavaScript when attempting to update said custom field via bug_actiongroup_page.php.
An XSS issue was discovered in MantisBT before 2.24.2. Improper escaping on view_all_bug_page.php allows a remote attacker to inject arbitrary HTML into the page by saving it into a text Custom Field, leading to possible code execution in the browser of any user subsequently viewing the issue (if CSP settings allow it).
The proj_doc_edit_page.php Project Documentation feature in MantisBT before 2.21.3 has a stored cross-site scripting (XSS) vulnerability, allowing execution of arbitrary code (if CSP settings permit it) after uploading an attachment with a crafted filename. The code is executed when editing the document's page.
The Timeline feature in my_view_page.php in MantisBT through 2.21.1 has a stored cross-site scripting (XSS) vulnerability, allowing execution of arbitrary code (if CSP settings permit it) after uploading an attachment with a crafted filename. The code is executed for any user having visibility to the issue, whenever My View Page is displayed.