SeaMonkey is an open source Web browser, email and newsgroup client, IRC chat client, and HTML editor.
A flaw was found in the way that SeaMonkey parsed malformed HTML mail messages. If a user opened a specially-crafted HTML mail message, it could cause SeaMonkey to crash or, possibly, to execute arbitrary code as the user running SeaMonkey. (CVE-2009-2210)
All SeaMonkey users should upgrade to these updated packages, which correct this issue. After installing the update, SeaMonkey must be restarted for the changes to take effect.