Internet Information Services Vulnerability - CVE-2009-4444

Microsoft Internet Information Services (IIS) 5.x and 6.x uses only the portion of a filename before a (semicolon) character to determine the file extension which allows remote attackers to bypass intended extension restrictions of third-party upload applications via a filename with a (1) .asp (2) .cer or (3) .asa first extension followed by a semicolon and a safe extension as demonstrated by the use of asp.dll to handle a .asp.jpg file.