The remote host has a web browser installed that is vulnerable to a heap overflow.
Versions of Mozilla Firefox prior to 1.7.5 are vulnerable to a heap overflow against its NNTP functionality. This may allow an attacker to execute arbitrary code on the remote host. To exploit this flaw, an attacker would need to set up a rogue website and lure a victim on the remote host into visiting it.
Upgrade to Mozilla Firefox 1.7.5 or later.