Exploit code has been published that could take advantage of <A HREF="http://news.zdnet.com/2100-1009_22-5958846.html?tag=zdnn.alert">flaws in Windows XP SP1 and Windows 2000 SP4,</A> according to a warning issued Thursday by Microsoft. Although the exploit code could be used to launch a denial-of-service attack in machines running XP SP1 and Windows 2000 with all service pack versions, the threat is only moderately severe, said Stephen Manzuik, a product manager at security research company eEye Digital Security.