Open source programmer Brian Mastenbrook has discovered a security flaw in the way that Safari handles RSS feeds. The vulnerability, which affects both Mac and Windows versions of Safari, could allow a malicious website to gain access to sensitive user data.

I have discovered that Apple's Safari browser is vulnerable to an attack that allows a malicious web site to read files on a user's hard drive without user intervention. This can be used to gain access to sensitive information stored on the user's computer, such as emails, passwords, or cookies that could be used to gain access to the user's accounts on some web sites. The vulnerability has been acknowledged by Apple.

Mastenbrook reports that all OS X 10.5 Leopard users, regardless of whether they use Safari or RSS feeds, should protect themselves by choosing an application other than Safari for reading RSS feeds, an option available in the "RSS" tab of Safari's Preferences. Safari for Windows users should utilize a different browser until Apple issues a patch. Mastenbrook, who has received credit from Apple for reporting a number of security issues over the past year, says that Apple has not given a timeframe for a fix.