The remote host is missing an update to thunderbird announced via advisory USN-782-1.

The problem can be corrected by upgrading your system to the following package versions: Ubuntu 8.04 LTS: thunderbird 2.0.0.22+build1+nobinonly-0ubuntu0.8.04.1 Ubuntu 8.10: thunderbird 2.0.0.22+build1+nobinonly-0ubuntu0.8.10.1 Ubuntu 9.04: thunderbird 2.0.0.22+build1+nobinonly-0ubuntu0.9.04.1 After a standard system upgrade you need to restart Thunderbird to effect the necessary changes. https://secure1.securityspace.com/smysecure/catid.html?in=USN-782-1

Several flaws were discovered in the JavaScript engine of Thunderbird. If a user had JavaScript enabled and were tricked into viewing malicious web content, a remote attacker could cause a denial of service or possibly execute arbitrary code with the privileges of the user invoking the program. (CVE-2009-1303, CVE-2009-1305, CVE-2009-1392, CVE-2009-1833, CVE-2009-1838) Several flaws were discovered in the way Thunderbird processed malformed URI schemes. If a user were tricked into viewing a malicious website and had JavaScript and plugins enabled, a remote attacker could execute arbitrary JavaScript or steal private data. (CVE-2009-1306, CVE-2009-1307, CVE-2009-1309) Cefn Hoile discovered Thunderbird did not adequately protect against embedded third-party stylesheets. If JavaScript were enabled, an attacker could exploit this to perform script injection attacks using XBL bindings. (CVE-2009-1308) Shuo Chen, Ziqing Mao, Yi-Min Wang, and Ming Zhang discovered that Thunderbird did not properly handle error responses when connecting to a proxy server. If a user had JavaScript enabled while using Thunderbird to view websites and a remote attacker were able to perform a man-in-the-middle attack, this flaw could be exploited to view sensitive information. (CVE-2009-1836) It was discovered that Thunderbird could be made to run scripts with elevated privileges. If a user had JavaScript enabled while having certain non-default add-ons installed and were tricked into viewing a malicious website, an attacker could cause a chrome privileged object, such as the browser sidebar, to run arbitrary code via interactions with the attacker controlled website. (CVE-2009-1841)