Better Comments < 1.5.6 - Subscriber+ Stored XSS

Description The plugin does not sanitise and escape some of its settings, which could allow low privilege users such as Subscribers to perform Stored Cross-Site Scripting attacks.

PoC

1. From the menu on the left, go into “Users” and edit Subscriber user. 2. Upload a new avatar image and click “Update User”. 3. Change the nickname to the following payload and click “Update User” as before: "onload="prompt(‘XSS’) 4. Payload is triggered immediately on Profile menu. 5. Open any post as the Subscriber user and leave a comment to trigger the payload. 6. Everywhere where the avatar is used, the payload is triggered. For example, consider the avatar is always used in the top right corner besides the username on any WordPress page or post.