Google security engineer Tavis Ormandy's disclosure in May was controversial because he posted technical information on the Web that described the bug in the Windows operating system, which some experts said could help malicious hackers launch attacks, before Microsoft had released software to fix it.
Officials with Microsoft declined to comment when asked if they believed Ormandy's disclosure of the vulnerability had led to the attacks.
Ormandy also drew attention because he lashed out in a blog posting at long-time Google rival Microsoft, saying that its security division was difficult to work with. He advised other researchers to use pseudonyms and anonymous email when communicating with the software maker.
"It leaves a slightly bad taste in the mouth to see somebody who is a Google security researcher have a pop at Microsoft," said Graham Cluley, an independent security researcher.
Ormandy could not be reached. A Google spokesman declined comment, saying that Ormandy's Windows project was personal and not related to his work for the company.