NWFILTER.SYS in Novell Client 4.91 SP 1 through SP 4 for Windows 2000, XP, and Server 2003 makes the \.\nwfilter device available for arbitrary user-mode input via METHOD_NEITHER IOCTLs, which allows local users to gain privileges by passing a kernel address as an argument and overwriting kernel memory locations.

More... (http://nvd.nist.gov/nvd.cfm?cvename=CVE-2007-5667)