Nessus 6.6.2 - 6.10.3 contains a flaw related to insecure permissions that may allow a local attacker to escalate privileges when the software is running in Agent Mode. Version 6.10.4 fixes this issue.
https://www.tenable.com/security/tns-2017-08
https://aspe1337.blogspot.nl/2017/04/writeup-of-cve-2017-7199.html