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Ubuntu Security Notice USN-4110-3
August 28, 2019

Dovecot regression
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A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 19.04
- Ubuntu 18.04 LTS
- Ubuntu 16.04 LTS

Summary:

USN-4110-1 introduced a regression in Dovecot.

Software Description:
- dovecot: IMAP and POP3 email server

Details:

USN-4110-1 fixed a vulnerability in Dovecot. The update introduced a
regression causing a wrong check. This update fixes the problem.

We apologize for the inconvenience.

Original advisory 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                    1:2.3.4.1-1ubuntu2.4

Ubuntu 18.04 LTS:
  dovecot-core                    1:2.2.33.2-1ubuntu4.5

Ubuntu 16.04 LTS:
  dovecot-core                    1:2.2.22-1ubuntu2.12

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

References:
  https://usn.ubuntu.com/4110-3
  https://usn.ubuntu.com/4110-1
  CVE-2019-11500

Package Information:
  https://launchpad.net/ubuntu/+source/dovecot/1:2.3.4.1-1ubuntu2.4
  https://launchpad.net/ubuntu/+source/dovecot/1:2.2.33.2-1ubuntu4.5
  https://launchpad.net/ubuntu/+source/dovecot/1:2.2.22-1ubuntu2.12