Description
WordPress is prone to a Denial of Service vulnerability which can be exploited by malicious people to cause the affected website to consume memory and CPU resources, thus denying service to legitimate users. WordPress versions 3.9.x ranging from 3.9 and up to (and including) 3.9.23 are vulnerable.
Remediation
Evaluate and apply the suggested patch
References
https://baraktawily.blogspot.ro/2018/02/how-to-dos-29-of-world-wide-websites.html
https://www.youtube.com/watch?v=nNDsGTalXS0
https://github.com/Quitten/WordPress/blob/master/wp-dos-patch.sh
https://www.exploit-db.com/exploits/43968/
https://packetstormsecurity.com/files/146249/WordPress-Core-Denial-Of-Service.html
https://www.rastating.com/protecting-wordpress-against-cve-2018-6389/