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Ubuntu Security Notice USN-4366-1
May 19, 2020

exim4 vulnerability
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A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 20.04 LTS
- Ubuntu 19.10
- Ubuntu 18.04 LTS
- Ubuntu 16.04 LTS
- Ubuntu 14.04 ESM

Summary:

Exim could be made to access sensitive information or bypass
authentication if it received a specially crafted input.

Software Description:
- exim4: Exim is a mail transport agent

Details:

It was discovered that Exim incorrectly handled certain inputs.
An remote attacker could possibly use this issue to access sensitive
information or authentication bypass.

Update instructions:

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

Ubuntu 20.04 LTS:
  exim4-base                      4.93-13ubuntu1.1
  exim4-daemon-heavy              4.93-13ubuntu1.1
  exim4-daemon-light              4.93-13ubuntu1.1

Ubuntu 19.10:
  exim4-base                      4.92.1-1ubuntu3.1
  exim4-daemon-heavy              4.92.1-1ubuntu3.1
  exim4-daemon-light              4.92.1-1ubuntu3.1

Ubuntu 18.04 LTS:
  exim4-base                      4.90.1-1ubuntu1.5
  exim4-daemon-heavy              4.90.1-1ubuntu1.5
  exim4-daemon-light              4.90.1-1ubuntu1.5

Ubuntu 16.04 LTS:
  exim4-base                      4.86.2-2ubuntu2.6
  exim4-daemon-heavy              4.86.2-2ubuntu2.6
  exim4-daemon-light              4.86.2-2ubuntu2.6

Ubuntu 14.04 ESM:
  exim4-base                      4.82-3ubuntu2.4+esm2
  exim4-daemon-heavy              4.82-3ubuntu2.4+esm2
  exim4-daemon-light              4.82-3ubuntu2.4+esm2

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

References:
  https://usn.ubuntu.com/4366-1
  CVE-2020-12783

Package Information:
  https://launchpad.net/ubuntu/+source/exim4/4.93-13ubuntu1.1
  https://launchpad.net/ubuntu/+source/exim4/4.92.1-1ubuntu3.1
  https://launchpad.net/ubuntu/+source/exim4/4.90.1-1ubuntu1.5
  https://launchpad.net/ubuntu/+source/exim4/4.86.2-2ubuntu2.6