Apple has released Safari 5.0.2 and Safari 4.1.2 (the former for users running Mac OS X 10.5 Leopard or later, the latter for users still running 10.4 Tiger). The updates patch a pair of vulnerabilities that could allow maliciously crafted Web sites to execute their own code or crash Safari. Beyond the security fixes, both updates correct issues with submitting forms. Safari 5.0.2 also addresses bugs with viewing Google Image results with Flash 10.1 installed, and uses an encrypted connection when surfing the Safari Extensions Gallery. The updates are available via Software Update or direct
download from Apple, and are recommended for all Safari users. (Free update, 37.56 MB for Snow Leopard, 46.71 MB for Leopard, 29.46 MB for Tiger)
Note that yesterday the Safari 4.1.2 download link on Apple's support page was linked to the old 4.1 version. Haven't tried since then.