The Product Addons and Product Options With Custom Fields WordPress plugin before 1.6.15 does...

The Product Addons and Product Options With Custom Fields WordPress plugin before 1.6.15 does not restrict an unauthenticated file-upload endpoint and accepts SVG files that are stored and served inline, allowing an unauthenticated attacker to upload a malicious SVG whose embedded script executes in the session of any user (such as an administrator) who later opens the file.