A researcher today unveiled an unpatched vulnerability in Internet Explorer (IE) that could allow an attacker remote access to victims' local files, but Microsoft downplayed its severity.

According to an advisory posted on XDisclose, the "critical" flaw is related to the way that IE processes different HTML tags, such as "img," "script," "embed," "object," "param," "body" and "input." The bug was discovered by Rajesh Sethumadhavan, a research engineer from India.

"By using the file protocol along with (these) tags, it is possible to access victims’ local files," according to the XDisclose advisory.

The vulnerability exists in IE6 and is possible in other versions of the browser. For success, an attacker must dupe a PC user into visiting a website containing the malicious code, according to the advisory.

A Microsoft spokesman told SCMagazine.com today the software giant has confirmed the vulnerability but that it cannot be exploited to allow an attacker to "receive files from an affected system," only to detect them.

"In addition, the attacker must know the location of the file in advance," the spokesman said. "This behavior is by design in current versions of (IE)."

The revelation came less than a week after Redmond issued a dozen patches addressing 20 vulnerabilities.

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