Most of the security components in the Mavericks release are not currently available in the most recent OS X 10.8 update, which provides a good reason for users of older OS X versions to update as soon as possible. The last OS X 10.8 Mountain Lion release prior to this week’s 10.9 Mavericks update is the 10.8.5 release which debuted in September.
One of the new updates in 10.9 is a fix for a vulnerability in OS X’s application firewall. The flaw is identified as CVE-2013-5165 and has an exploitability score of 10, meaning it can be remotely exploited by an attacker without authentication. Apple’s security notification on the issue explains that “the –blockApp option did not properly block applications from receiving network connections.”