Amazon Linux AMI Security Advisory: ALAS-2017-855
Advisory Release Date: 2017-07-06 22:56 Pacific
It was found that the original fix for CVE-2017-1000367 was incomplete. A flaw was found in the way sudo parsed tty information from the process status file in the proc filesystem. A local user with privileges to execute commands via sudo could use this flaw to escalate their privileges to root. (CVE-2017-1000368 )
Run yum update sudo to update your system.