Apple has released a minor update to OS X Mountain Lion, fixing "an issue with Keychain that can affect 2012 Mac systems." The update weighs in at 26.65MB and can be downloaded through Apple's support site or the Mac App Store.
About OS X Mountain Lion 10.8.2 Supplemental Update 2.0
This update addresses an issue with Keychain that can affect 2012 Mac systems.
This update is recommended for all Mac systems introduced in 2012.
Apple previously released OS X v10.8.2 Supplemental Update 1.0 at the beginning of October.