Cross-Site Scripting (XSS) vulnerability in Roundcube Webmail 1.6.9 allows remote authenticated users to upload a malicious file as an email attachment, leading to the triggering of the XSS by visiting the SENT session.
The product receives input from an upstream component, but it does not neutralize or incorrectly neutralizes special characters such as "<", ">", and "&" that could be interpreted as web-scripting elements when they are sent to a downstream component that processes web pages.