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Ubuntu Security Notice USN-4110-1
August 28, 2019

dovecot vulnerability
=========================================================================
A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 19.04
- Ubuntu 18.04 LTS
- Ubuntu 16.04 LTS

Summary:

Dovecot could be made to crash or execute arbitrary code if it
received a specially crafted data.

Software Description:
- dovecot: IMAP and POP3 email server

Details:

Nick Roessler and Rafi Rubin discovered that Dovecot incorrectly
handled certain data. An attacker could possibly use this issue
to cause a denial of service or execute arbitrary code.

Update instructions:

The problem can be corrected by updating your system to the following
package versions:

Ubuntu 19.04:
  dovecot-core                    1:2.3.4.1-1ubuntu2.3

Ubuntu 18.04 LTS:
  dovecot-core                    1:2.2.33.2-1ubuntu4.4

Ubuntu 16.04 LTS:
  dovecot-core                    1:2.2.22-1ubuntu2.11

In general, a standard system update will make all the necessary changes.

References:
  https://usn.ubuntu.com/4110-1
  CVE-2019-11500

Package Information:
  https://launchpad.net/ubuntu/+source/dovecot/1:2.3.4.1-1ubuntu2.3
  https://launchpad.net/ubuntu/+source/dovecot/1:2.2.33.2-1ubuntu4.4
  https://launchpad.net/ubuntu/+source/dovecot/1:2.2.22-1ubuntu2.11