In an interesting twist on browser-based security issues, security researchers said they have found a flaw in which Microsoft's Internet Explorer can cause Mozilla's Firefox to execute remote malicious code. Security firm Secunia released an advisory Tuesday, ranking the flaw as highly critical. The vulnerability is confirmed on Firefox 2.0.0.4 on a fully-patched version of Windows XP SP2. Basically, the end user must use IE to navigate to a malicious Web page and click on a link. The problem only occurs when the user also has Firefox installed.