The crontab script in the ntp package before 1:4.2.6.p3+dfsg-1ubuntu3.11 on Ubuntu 12.04 LTS, before 1:4.2.6.p5+dfsg-3ubuntu2.14.04.10 on Ubuntu 14.04 LTS, on Ubuntu Wily, and before 1:4.2.8p4+dfsg-3ubuntu5.3 on Ubuntu 16.04 LTS allows local users with access to the ntp account to write to arbitrary files and consequently gain privileges via vectors involving statistics directory cleanup.