Microsoft will release two critical fixes for vulnerabilities in its Windows and Internet Explorer (IE) services for its August Patch Tuesday.

The August Patch Tuesday update is due to arrive on 12 August and will feature at least nine security fixes. The IE and Windows patches are the only two to hold a "critical" rating from Microsoft and leave users open to remote code-execution attacks.

Wolfgang Kandek, CTO of Qualys, said the IE flaw is the more serious of the two as it affects all versions of the web browser, while the Windows bug is limited to a more specific set of users.

"The most critical patch is bulletin one, which affects all versions of IE. Since browsers are the attackers' favorite targets, this patch should be top of your list. An attacker could exploit this vulnerability through a malicious webpage," he explained.

"Bulletin two is a critical update for Windows and affects Windows 7 and Windows 8, plus the Media Center TV Pack for Vista. I believe it must be addressing bugs in the graphics-processing pipeline, most likely in an online video component."

The remaining seven vulnerabilities related to Microsoft's Office, SQL server, Windows, Server and .Net framework services. Each holds an "important" rating from Microsoft and leaves users open to a mix of remote code-execution, elevation of privilege and security-bypass exploits.