Apple also patched Macs running Lion and Snow Leopard with Security Update 2013-001. The Snow Leopard update was notable because it arrived a record eight months after the introduction of Mountain Lion, reinforcing the idea that Apple has changed its support policy and will patch "n-2," where "n" is the current edition of OS X.
Traditionally, Apple has dropped support of n-2 upon the launch of n, but the back-to-back releases of Lion and Mountain Lion in 2011 and 2012, and the refusal of Snow Leopard to go away -- in February, it powered nearly 28% of all Macs -- has apparently altered Apple's policy.
OS X 10.8.3 and Security Update 2013-001 are available by selecting "Software Update..." from the Apple menu, or by opening the Mac App Store application and clicking the Update icon at the top right of the screen. The updates can also be downloaded manually from Apple's support site.
Gregg Keizer covers Microsoft, security issues, Apple, Web browsers and general technology breaking news for Computerworld. Follow Gregg on Twitter at @gkeizer, on Google+ or subscribe to Gregg's RSS feed. His email address is firstname.lastname@example.org.
Read more about mac os x in Computerworld's Mac OS X Topic Center.