More critical holes were found in Windows XP

Symantec acted after security researchers published the details of the heap overflow vulnerabilities in messages posted to online security news groups Thursday, including the Bugtraq mailing list, and on xfocus.net. The flaws affect most supported versions of Windows, but Microsoft has not yet issued a patch for the newly disclosed holes. Windows users are vulnerable to Internet based attacks until patches are issued, Symantec said.

In overflow vulnerabilities, storage areas in a computer's memory are exceeded, allowing random data or malicious code to be placed on the computer when certain types of data are used to flood the memory buffer.