Which browser is the riskiest? The answer may surprise you.

Microsoft's efforts to solve server-side Web vulnerabilities and to patch its Internet Explorer client, may be paying off. While IE is still the most widely used browser for viewing content on the Internet--and thus, the most widely targeted for assaults--it had the second best ranking among the top four browsers in sidestepping vulnerabilities, according to a new study.

The report, from application security firm Cenzic, analyzed a number of Web security issues reported in the first half of this year. The browser comparison was only one part of the study, called, "Web Application Security Trends Report: Q1-Q2, 2009" (PDF download).

Firefox was the most vulnerable browser, logging 44 percent of the total vulnerabilities found, according to the report. Safari, at 35 percent, ranked next to Firefox at the bottom. IE had 15 percent of the vulnerabilities, and Opera only 6 percent.

Firefox, Microsoft's most robust rival in the browser market, reportedly has an estimated 330 million users and recently passed its fifth anniversary.

IE is still the most-used browser, followed by Firefox, Apple Safari, Google Chrome (which Cenzic didn't study) and Opera. GNC