A critical zero-day vulnerability has been discovered in all versions of Apple’s OS X operating system that allows hackers to exploit the company’s newest protection feature. The vulnerability (CVE-2016-1757) is a Non-Memory Corruption bug. Apple has patched the vulnerability, but only in updates for El Capitan 10.11.4, and iOS 9.3 that were released on 21st March. Other versions do not appear to have a patch update for this specific vulnerability from Apple, meaning they are left vulnerable to this specific bug.
Source: https://thehackernews.com/2016/03/system-integrity-protection.html