Microsoft Help and Support Center Bypass Vulnerability:

Microsoft Help and Support Center contains a programming error that may allow a remote attacker to bypass security restrictions on an affected system. The error occurs when invalid hex-encoded characters are used as a parameter to a search query using the hcp:// URI schema.

Changelogs here: http://www.snort.org/vrt/advisories/2010/06/10/vrt-rules-2010-06-10.html/