Tavis Ormandy published his advisory, including exploit code, just five days after reporting the vulnerability to Microsoft.
Ormandy defended the decision to make a full disclosure, saying: "I've concluded that there is a significant possibility that attackers have studied this component, and releasing this information rapidly is in the best interest of security."
But Microsoft said it continues to encourage responsible disclosure.
"Reporting vulnerabilities directly to vendors without further disclosure helps ensure that customers receive comprehensive, high-quality updates before cybercriminals learn of - and work to exploit - a vulnerability," a Microsoft spokesman said.
"Responsible disclosure protects the computer ecosystem and individual computer users from harm," he added.
Microsoft is investigating public disclosure of the vulnerability and said it will release more information once the extent of the issue has been determined.