Mozilla Thunderbird is a standalone mail and newsgroup client.
Several denial of service flaws were found in the way Thunderbird handled certain form and cookie data. A malicious web site that is able to set arbitrary form and cookie data could prevent Thunderbird from functioning properly. (CVE-2007-1362, CVE-2007-2869)
A flaw was found in the way Thunderbird processed certain APOP authentication requests. By sending certain responses when Thunderbird attempted to authenticate against an APOP server, a remote attacker could potentially acquire certain portions of a user's authentication credentials. (CVE-2007-1558)
A flaw was found in the way Thunderbird displayed certain web content. A malicious web page could generate content which could overlay user interface elements such as the hostname and security indicators, tricking users into thinking they are visiting a different site. (CVE-2007-2871)
Users of Thunderbird are advised to apply this update, which contains Thunderbird version 126.96.36.199 that corrects these issues.