Microsoft Corp. is investigating a new set of potentially serious security flaws in Internet Explorer and Outlook reported by security company eEye Digital Security Inc., the software maker said Friday.

The two flaws in the Web browser and e-mail client could let an attacker take control over a system with minimal action from the user, eEye said in two security alerts posted on its page of upcoming advisories. The company ranks the flaws "high" risk.

One of the vulnerabilities could let an attacker compromise a user's machine after the user clicks on a Web link, said Marc Maiffret, co-founder and chief hacking officer at eEye. "Nothing that would be normally suspicious to the user," he said. The flaws affect both Outlook and Outlook Express, according to Maiffret.

The flaws exist in the default installations of the applications on most current versions of Windows, according to eEye of Aliso Viejo, California. The company has informed Microsoft and will not provide further details until Microsoft has provided a patch or security alert, it said on its Web site.

"We keep all the details private until Microsoft produces a patch. But that is not to say that nobody else has discovered the vulnerability and produced an exploit," Maiffret said. However, eEye has not seen any attacks that take advantage of the flaws yet, he said.

Microsoft is investigating the privately reported possible vulnerabilities, a spokeswoman for the Redmond, Washington, software maker said. The company is not aware of any attempts to exploit the vulnerabilities, she said.

Upon the completion of the investigation, Microsoft will take the appropriate action to protect users. That could be a fix as part of the company's monthly patching cycle, a fix in the next service pack or a special update, the spokeswoman said.

EEye reported the flaws to Microsoft on March 16 and March 29, according to the eEye Web site. Maiffret hopes Microsoft will produce a patch within two months, the industry standard time for delivering a fix, he said.