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Actually, OS X Security Update 2015-004 (see https://support.apple.com/en-gb/HT204659 ) which includes the CVE-2015-1130 fix, has been released for 10.8.5, 10.9.5 and 10.10.x, so in theory all these releases are still supported. However, not all of the fixes in it apply to all these OS X versions, so in practice, maybe not?