SeaMonkey is an open source web browser, email and newsgroup client, IRC chat client, and HTML editor. A flaw was found in the way SeaMonkey handled frame objects with certain names. An attacker could use this flaw to cause a plug-in to grant its content access to another site or the local file system, violating the same-origin policy. An integer underflow flaw was found in the way SeaMonkey handled large JavaScript regular expressions. A web page containing malicious JavaScript could cause SeaMonkey to access already freed memory, causing SeaMonkey to crash or, potentially, execute arbitrary code with the privileges of the user running SeaMonkey. All SeaMonkey users should upgrade to these updated packages, which correct these issues. After installing the update, SeaMonkey must be restarted for the changes to take effect.