Integer overflow error when processing SID files and other flaws within these files affect Express View Browser plug-in users. Those vulnerabilities were rated as „highly critical“ allowing attacker to compromise user’s system. A successful attack allows to execute arbitrary code but requires to entice user to visit malicious website.
Flaws were confirmed in version 6.5.0.3300. Users should turn the plugin off.

Source: Secunia
12.01.2012