Ubuntu Security Notice USN-3258-2
11th April, 2017
A security issue affects these releases of Ubuntu and its
- Ubuntu 16.10
- Ubuntu 16.04 LTS
USN-3258-1 introduced a regression in Dovecot.
– IMAP and POP3 email server
USN-3258-1 intended to fix a vulnerability in Dovecot. Further investigation
revealed that only Dovecot versions 2.2.26 and newer were affected by the
vulnerability. Additionally, the change introduced a regression when Dovecot
was configured to use the “dict” authentication database. This update reverts
the change. We apologize for the inconvenience.
Original advisory details:
It was discovered that Dovecot incorrectly handled some usernames. An attacker
could possibly use this issue to cause Dovecot to hang or crash, resulting in a
denial of service.
The problem can be corrected by updating your system to the following
To update your system, please follow these instructions:
In general, a standard system update will make all the necessary changes.