The Mozilla Foundation released the newest version of the Thunderbird email client, v.17.0.3, today for Windows, Linux, and Mac operating systems. This version patches several critical security vulnerabilities that could allow an attacker to execute arbitrary code, bypass security features, or cause a denial-of-service condition. All users of Thunderbird are strongly advised to update to the newest version immediately.

The Release Notes for Thunderbird v.17.0.3 can be found at https://www.mozilla.org/en-US/thunderbird/17.0.3/releasenotes/ and a complete list of changes and fixes can be found at Bugzilla.

Current users of Thunderbird can update to the newest version directly from their Thunderbird email client by going to HELP » DOWNLOAD UPDATE.  If you do not currently have Thunderbird installed you can obtain the installer for the newest version at https://www.mozilla.org/en-US/thunderbird/.