An anonymous reader writes "Microsoft said late Wednesday that it plans to release a critical security update today to plug a security hole present in all supported versions of Windows. The company hasn't released any details about the patch yet, which is expected to be pushed out at 1 p.m. PT. Normally, Redmond issues security updates on Patch Tuesday, the second Tuesday of each month. The Washington Post's Security Fix blog notes that each of the three times in the past that Microsoft has departed from its patch cycle, it was to fix some really nasty vulnerability that criminals already were exploiting to break into Windows PCs." Reader filenavigator points out an article which describes the hole as an SMB vulnerability, and says it "allows anyone to access a Windows machine remotely without any user name or password. Any machine that exposes Windows file sharing is vulnerable." Update: 10/23 17:42 GMT by T : Reader AngryDad adds a link to Microsoft's more detailed memo.