The company is investigating claims of a "possible denial-of-service vulnerability in Windows Server Message Block (SMB)," the Microsoft spokesperson said, adding that the company was unaware of any attacks trying to exploit the hole.
The bug triggers an infinite loop on the Server Message Block (SMB) protocol used for sharing files in Windows, researcher Laurent Gaffié wrote in a posting on the Full-Disclosure mailing list and on a blog.
For more, read "Microsoft probing Windows 7 zero-day hole" on CNET News.