Safari 5.0 includes new functionality, but also plugs at least 48 different security vulnerabilities that could be exploited by hackers. Mac OS X version 10.4 users (which Safari 5 doesn’t support) arent left in the lurch. Apple has also issued Safari version 4.1 for those customers, which addresses the same set of security issues. If you dawdle over updating your computer, its possible that hackers could exploit the security bugs including some that could mean that simply visiting a booby-trapped webpage could lead to”]
Source: https://grahamcluley.com/swarm-safari-security-holes-mac-windows-users-told-update/