The terse warning posted to eEye's Upcoming Advisories site tags Publisher 2007, the desktop and Web publishing program included with some editions of Office, as the flawed application. "A remotely exploitable flaw exists within Publisher 2007 that allows arbitrary code to be executed in the context of the logged in user," the alert read. eEye rated the vulnerability as "high," and reported it to Microsoft a week ago.

"We're still in the back-and-forth with Microsoft [Security Response Center]," said Marc Maiffret, eEye's chief technology officer.

Microsoft confirmed it is working with eEye. "Microsoft is investigating new reports of a possible vulnerability in Publisher 2007, which has been responsibly disclosed to Microsoft [and] will continue to work with eEye to further understand this report," said a Microsoft spokesperson. "[We are] not aware of any attacks attempting to use the reported vulnerability or of customer impact at this time."

Although Maiffret declined to provide details of the vulnerability, he tacitly acknowledged that it was a bug in the Publisher 2007 file format. "Ninety percent of the time, [Office] bugs are in file formats. This is basically the same."

Users of Microsoft's Office productivity suites -- going as far back as Office 2000 and including the more recent Office 2003 -- have confronted a flood of flaws in the last 14 months. During 2006, Microsoft unveiled 13 security updates for Office 2000 and 11 for Office 2003; in the first two months of 2007, it's rolled out four bulletins for Office 2000 and six for Office 2003.