Apple last week advised users to upgrade following the discovery that various versions of Mac OS X, Safari web browser, Apple Mail, and other products are affected by multiple security vulnerabilities. Users of Apple Mac OS X version 10.3.9 (Panther) and version 10.4.5 (Tiger) are confirmed to be at risk.
Older versions of Mac OS X might also be exposed to various security flaws, the most serious of which creates a means for hackers to load malicious code onto vulnerable computers. Although the flaws are not the current subject of hacking attacks, it still makes sense to upgrade.
Users who haven't had their OS software updated automatically through the Apple Update service are advised to apply security patches, as explained in an Apple's technical advisory here. Security clearing house US CERT further advises Safari fans to disable the "Open 'safe' files after downloading" option on their browser as an added precaution.
QuickTime aficionados - whether they use the popular media viewer software on Mac or Windows platforms - also needs to upgrade, again because of security flaws. Apple QuickTime 7.1 corrects several image and media file handling vulnerabilities that create a means for hackers to run hostile code on vulnerable systems.