Just a week after Microsoft released its latest batch of security patches comes a report of a new critical flaw in PowerPoint 2003.

The use of the malicious code could seriously compromise a PC, according to Microsoft. Alexandra Huft, a Microsoft Security Response rep posted the following on the Center's blog: “I wanted to let you know that we've been made aware of proof of concept code published publicly affecting Microsoft Office 2003 PowerPoint. We are currently investigating this report".

“The reported proof of concept may allow an attacker to execute code on a user's machine by convincing them to open a specially-crafted PowerPoint file."

“We are not aware of any attacks attempting to use the reported vulnerability or of customer impact at this time.”

Security monitoring company Secunia rated the bug “highly critical”, while FrSIRT labelled it “critical”.

Office seems a particularly popular target for hackers recently; 16 flaws were patched in last week's security release.