Improper filtering of javascript in HTML feed-view — Mozilla

Security researcher Mario Heiderich reported that javascript could be executed in the HTML feed-view using tag within the RSS . This problem is due to tags not being filtered out during parsing and can lead to a potential cross-site scripting (XSS) attack. The flaw existed in a parser utility class and could affect other parts of the browser or add-ons which rely on that class to sanitize untrusted input.