USN-6190-2: AccountsService vulnerability

USN-6190-1 fixed a vulnerability in AccountsService. This update provides
the corresponding update for Ubuntu 14.04 LTS, Ubuntu 16.04 LTS and
Ubuntu 18.04 LTS.

Original advisory details:

Kevin Backhouse discovered that AccountsService incorrectly handled certain
D-Bus messages. A local attacker could use this issue to cause
AccountsService to crash, resulting in a denial of service, or possibly
execute arbitrary code.

advisory attacker bus crash d-bus denial of service issue kevin local lts messages service ubuntu update usn vulnerability