==========================================================================
Ubuntu Security Notice USN-6411-1
October 04, 2023

exim4 vulnerabilities
==========================================================================

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

- Ubuntu 23.04
- Ubuntu 22.04 LTS
- Ubuntu 20.04 LTS
- Ubuntu 18.04 LTS (Available with Ubuntu Pro)
- Ubuntu 16.04 LTS (Available with Ubuntu Pro)
- Ubuntu 14.04 LTS (Available with Ubuntu Pro)

Summary:

Several security issues were fixed in Exim.

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

Details:

It was discovered that Exim incorrectly handled certain challenge requests.
A remote attacker could possibly use this issue to perform out-of-bounds
reads, resulting in information leakage. (CVE-2023-42114)

It was discovered that Exim incorrectly handled validation of user-supplied
data. A remote attacker could possibly use this issue to perform
out-of-bounds writes, resulting in arbitrary code execution. This issue
only affected Ubuntu 20.04 LTS, Ubuntu 22.04 LTS and Ubuntu 23.04.
(CVE-2023-42115)

It was discovered that Exim incorrectly handled certain challenge requests.
A remote attacker could possibly use this issue to perform out-of-bounds
writes, resulting in arbitrary code execution. (CVE-2023-42116)

Update instructions:

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

Ubuntu 23.04:
   exim4                           4.96-14ubuntu1.2
   exim4-base                      4.96-14ubuntu1.2
   exim4-daemon-heavy              4.96-14ubuntu1.2
   exim4-daemon-light              4.96-14ubuntu1.2
   eximon4                         4.96-14ubuntu1.2

Ubuntu 22.04 LTS:
   exim4                           4.95-4ubuntu2.3
   exim4-base                      4.95-4ubuntu2.3
   exim4-daemon-heavy              4.95-4ubuntu2.3
   exim4-daemon-light              4.95-4ubuntu2.3
   eximon4                         4.95-4ubuntu2.3

Ubuntu 20.04 LTS:
   exim4                           4.93-13ubuntu1.8
   exim4-base                      4.93-13ubuntu1.8
   exim4-daemon-heavy              4.93-13ubuntu1.8
   exim4-daemon-light              4.93-13ubuntu1.8
   eximon4                         4.93-13ubuntu1.8

Ubuntu 18.04 LTS (Available with Ubuntu Pro):
   exim4                           4.90.1-1ubuntu1.10+esm1
   exim4-base                      4.90.1-1ubuntu1.10+esm1
   exim4-daemon-heavy              4.90.1-1ubuntu1.10+esm1
   exim4-daemon-light              4.90.1-1ubuntu1.10+esm1
   eximon4                         4.90.1-1ubuntu1.10+esm1

Ubuntu 16.04 LTS (Available with Ubuntu Pro):
   exim4                           4.86.2-2ubuntu2.6+esm4
   exim4-base                      4.86.2-2ubuntu2.6+esm4
   exim4-daemon-heavy              4.86.2-2ubuntu2.6+esm4
   exim4-daemon-light              4.86.2-2ubuntu2.6+esm4
   eximon4                         4.86.2-2ubuntu2.6+esm4

Ubuntu 14.04 LTS (Available with Ubuntu Pro):
   exim4                           4.82-3ubuntu2.4+esm6
   exim4-base                      4.82-3ubuntu2.4+esm6
   exim4-daemon-heavy              4.82-3ubuntu2.4+esm6
   exim4-daemon-light              4.82-3ubuntu2.4+esm6
   eximon4                         4.82-3ubuntu2.4+esm6

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

References:
   https://ubuntu.com/security/notices/USN-6411-1
   CVE-2023-42114, CVE-2023-42115, CVE-2023-42116

Package Information:
   https://launchpad.net/ubuntu/+source/exim4/4.96-14ubuntu1.2
   https://launchpad.net/ubuntu/+source/exim4/4.95-4ubuntu2.3
   https://launchpad.net/ubuntu/+source/exim4/4.93-13ubuntu1.8