The Tor Browser Team is proud to announce the first alpha release in the 5.5 series. The release is available for download in the 5.5a1 distribution directory and on the alpha download page.

This release features important security updates to Firefox. In particular, while the recent PDF.js exploit did not affect 4.5 users, it does affect users of 5.0a3 and 5.0a4. Although the High security level of the Security Slider also prevented the exploit from working against even those users, all alpha users are still strongly encouraged to upgrade as soon as possible.