Mozilla released a plan security update for Thunderbird on June 10th, 2014 with version 24.6.0. Information about these security fixes can be viewed here. Depending on the users update settings, they will be prompted to install the Thunderbird Update or may do so via Help > About Thunderbird. Users can also download and manually install the latest version of Mozilla Thunderbird via getthunderbird.com site.,
The next scheduled update for Thunderbird will be in about six-weeks with Thunderbird 24.7.0 on July 22nd, 2014.