A Stored Cross-Site Scripting (XSS) vulnerability exists in AvantFAX 3.3.7. An authenticated low privilege user can inject arbitrary Javascript into their e-mail address which is executed when an administrator logs into AvantFAX to view the admin dashboard. This may result in stealing an administrator's session cookie and hijacking their session.

An Information Disclosure vulnerability exists in AvantFAX 3.3.7. Backups of the AvantFAX sent/received faxes, and database backups are stored using the current date as the filename and hosted on the web server without access controls.

A File Upload vulnerability exists in AvantFAX 3.3.7. An authenticated user can bypass PHP file type validation in FileUpload.php by uploading a specially crafted PHP file.