The plugin did not sanitise the SVG files uploaded, which could allow low privilege users such as author+ to upload a malicious SVG and then perform XSS attacks by inducing another user to access the file directly. In v3.4, the plugin restricted such upload to editors and admin, with an option to also allow author to do so. The description of the plugin has also been updated with a security warning as upload of such content is intended.
Proof of Concept
As an author, upload a malicious SVG and then access it directly (ie https://example.com/wp-content/uploads/2021/06/xss.svg) to trigger the XSS