Dovecot could be made to expose sensitive information over the network.
It was discovered that Dovecot incorrectly handled client certificates. A remote attacker in possession of a valid certificate with an empty username field could possibly use this issue to impersonate other users.
5 February 2019
A security issue affects these releases of Ubuntu and its derivatives:
Dovecot could be made to expose sensitive information over the network.
It was discovered that Dovecot incorrectly handled client certificates. A remote attacker in possession of a valid certificate with an empty username field could possibly use this issue to impersonate other users.
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.
Vulmon