Authentication is not required to exploit this vulnerability. The specific flaw exists within imailsrv.exe which is invoked to handle messages sent to the imailsrv. When a message contains multiple "Reply-To:" headers the imailsrv.exe process concatenates these into a single fixed length buffer on the stack. No validation of the data or data length is done. A remote attacker can exploit this vulnerability to execute arbitrary code under the context of the SYSTEM user.
Disclosure Timeline:
2010-06-08 - Vulnerability reported to vendor
2010-07-15 - Coordinated public release of advisory
