An attacker could trick APT into installing altered packages.
It was discovered that APT incorrectly handled the mirror method (mirror://). If a remote attacker were able to perform a man-in-the-middle attack, this flaw could potentially be used to install altered packages in environments configured to use mirror:// entries.
20 August 2018
A security issue affects these releases of Ubuntu and its derivatives:
An attacker could trick APT into installing altered packages.
It was discovered that APT incorrectly handled the mirror method (mirror://). If a remote attacker were able to perform a man-in-the-middle attack, this flaw could potentially be used to install altered packages in environments configured to use mirror:// entries.
The problem can be corrected by updating your system to the following package versions:
To update your system, please follow these instructions: https://wiki.ubuntu.com/Security/Upgrades.
In general, a standard system update will make all the necessary changes.