In a look at the number of vulnerabilities recorded over 25 years in software products and open source, a researcher at Sourcefire has determined that Microsoft Windows XP and the Mozilla Firefox browser stand out as the two with the largest number of high-severity vulnerabilities.

Windows XP has had 453 while Firefox has had 433 vulnerabilities rated high and critical based on the Common Vulnerabilities and Exposures (CVE) database and the second source for the statistics, the National Vulnerability Database from the National Institute of Standards and Technology (NIST). High-severity vulnerabilities mean attackers can potentially fully compromise the user's machine. The total number of vulnerabilities for all the products and open-source software that has accumulated over 25 years has hit 50,000, according to Sourcefire and PCWorld, which is discussing the results of its research at the RSA Conference this week.

In the 25 years of recorded vulnerabilities examined this way, there was peak of 6612 vulnerabilities in 2006 but the worst year overall for high-severity ones was 2007 at 3159 out of a total of 6518, says Dr. Yves Younan, senior research engineer on Sourcefire's vulnerability research team.