The latest version of Thunderbird can be downloaded from Softpedia
On October 29, in a security notice Canonical published details about Thunderbird vulnerabilities for its Ubuntu 12.10, Ubuntu 12.04 LTS, Ubuntu 11.10, Ubuntu 11.04, and Ubuntu 10.04 LTS operating systems.According to Canonical, several security issues were fixed in Thunderbird, which allowed a remote attacker to conduct cross-site scripting (XSS) attacks or to exploit the vulnerability in order to bypass security protections and perform cross-origin reading of the Location object.
For a more detailed description of the security problems, you can visit Canonical's security notification.
Users can simply fix the security flaws by upgrading the operating systems to the Thunderbird package, specific to each distribution.
A normal system update, executed with the Update Manager, will implement all the necessary changes. A complete system restart is not necessary.
Users can also download Mozilla Thunderbird 16.0.2 right now from Softpedia.