http://secunia.com/advisories/29133/ - Multiple vulnerabilities were fixed in Thunderbird. These include heap overflows, information disclosure, directory traversal, privilege escalation and memory corruption crashes. These problems are fixed in version 18.104.22.168. It is worth mentioning that Thunderbird 1.5 is no longer supported. Mozilla has warned that these issues remain in Thunderbird 1.5.14 and are not scheduled to be fixed. It is recommended that all Thunderbird users upgrade to 22.214.171.124.