A new hardened Tor Browser release is available. It can be found in the 6.5a5-hardened distribution directory and on the download page for hardened builds.

This release features an important security update to Firefox and contains, in addition to that, an update to NoScript (2.9.5.2) and a fix of our updater code so it can handle unix domain sockets.

The Firefox security flaw responsible for this urgent release is already actively exploited on Windows systems. Even though there is currently, to the best of our knowledge, no similar exploit for OS X or Linux users available the underlying bug affects those platforms as well. Thus we strongly recommend that all users apply the update to their Tor Browser immediately. A restart is required for it to take effect.

Tor Browser users who had set their security slider to "High" are believed to have been safe from this vulnerability.

Note regarding updating: We still require the same update procedure as experienced during an update to 6.5a4-hardened: a dialog will be shown asking to either set `app.update.staging.enabled` or `extensions.torlauncher.control_port_use_ipc` and `extensions.torlauncher.socks_port_use_ipc` to `false` (and restart the browser in the latter case) before attempting to update. The fix for this problem is shipped with this release and we will be back to a normal update experience with the update to 6.5a6-hardened. We are sorry for this inconvenience.

Here is the full changelog since 6.5a5-hardened: