XSS viewing javascript: frames or images from context menu — Mozilla

Paul Nickerson demonstrated that if an attacker could convince a user to right-click on a broken image and choose “View Image” from the context menu then he could get javascript to run on a site of the attacker’s choosing by making the image src attribute a javascript: URL and loading the target site on mousedown. This could be used to steal login cookies or other confidential information from the target site.