Amazon Linux AMI Security Advisory: ALAS-2020-1379
Advisory Release Date: 2020-06-23 05:55 Pacific
Advisory Updated Date: 2020-06-26 04:47 Pacific
rbash in Bash before 4.4-beta2 did not prevent the shell user from modifying BASH_CMDS, thus allowing the user to execute any command with the permissions of the shell. (CVE-2019-9924 )
Run yum update bash to update your system.