Mozilla Thunderbird 31.6.0 fixes a use-after-free issue that occurred when using the Fluendo MP3 GStreamer plugin to play certain MP3 files, addresses an issue with loading of documents through the a resource:// URL, which loaded privileged chrome pages. A flaw in the CORS (Cross-Origin Resource Sharing) request has been repaired in order to no longer follow 30x redirections after preflight has been fixed, as well as a flaw with SVG content navigation, which could allow an attacker to bypass same-origin policy protections and run scripts as a privileged user.