Apart from security fixes, OS X 10.9.2 also includes a number of improvements such as adding ability to make and receive FaceTime audio calls, call waiting support in FaceTime, and ability to block iMessages from individual senders. Accessing SMB2 file servers has the reliability improved. (More detail at About the OS X Mavericks v10.9.2 Update page.)
Security Update 2014-001 fixes a serious SSL bug (CVE-2014-1266) that concerns data security. The SSL flaw allows an attacker to intercept and decrypt SSL/TLS communications (man-in-the-middle attack).
Those downloads are available from Apple's Software Update or following download pages.
OS X Mavericks 10.9.2 Update (859.7 MB)
OS X Mavericks 10.9.2 Update (Combo) (859.7 MB)
Security Update 2014-001 (Lion) (123.4 MB)
Security Update 2014-001 (Mountain Lion) (115.8 MB)
Security Update 2014-001 Server (Lion) (173.6 MB)
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