A new patch , the Security Update 2018-003, has recently been released on 1st june, which would fix some vulnerabilities afflicting Mac OS X High Sierra, Sierra, El Capitan.
Such vulnerabilities would allow, for example, a local attacker to gain elevated privileges on the system ,another one could allow a local user to bypass security restrictions.
There was also mentioned about of a non-specified validation defect in the kernel that an authenticated user could exploit to perform Ddos attacks.
You can refer to Apple security document HT208849