https://www.sentinelone.com/blog/apple-os-x-zero-day-vulnerability-can-bypass-system-integrity-protection/
(just sharing at this point; no advice to offer other than nag Apple)
Edit: CVE-2016-1757, as Rich notes below, is patched in 10.11.4 and Security Update 2016-002.
http://lists.apple.com/archives/security-announce/2016/Mar/msg00004.html
