In Bolt CMS before version 3.7.1, the filename of uploaded files was vulnerable to stored XSS. It is not possible to inject javascript code in the file name when creating/uploading the file. But, once created/uploaded, it can be renamed to inject the payload in it. Additionally, the measures to prevent renaming the file to disallowed filename extensions could be circumvented. This is fixed in Bolt 3.7.1.

The filename of uploaded files vulnerable to stored XSS in Bolt CMS

The filename of uploaded files vulnerable to stored XSS