Looks like there was a patch from MS's "patch Tuesday" yesterday that didn't involve Windows (directly), but rather an MS Office product: Excel. If you're running MS Office, time to head on over to the Office Update page....

"The patch dealing with the Office vulnerability contained fixes for five issues within Excel, including malformed range, file format parsing, description, graphic and record flaws. In each case, an attacker could take complete control of an affected system if the user was logged in as an administrator."