Microsoft has released a new security update for Windows NT 4.0/2000/XP

Remote Procedure Call (RPC) is a protocol used by the Windows operating system. RPC provides an inter-process communication mechanism that allows a program running on one computer to seamlessly execute code on a remote system. The protocol itself is derived from the OSF (Open Software Foundation) RPC protocol, but with the addition of some Microsoft specific extensions.

There is a vulnerability in the part of RPC that deals with message exchange over TCP/IP. The failure results because of incorrect handling of malformed messages. This particular vulnerabilty affects the RPC Endpoint Mapper process, which listens on TCP/IP port 135. The RPC endpoint mapper allows RPC clients to determine the port number currently assigned to a particular RPC service.

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