An Exim security update has been released for Ubuntu Linux 18.04 LTS, 20.04 LTS, 22.04 LTS, and 22.10.

USN-5741-1: Exim vulnerability

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Ubuntu Security Notice USN-5741-1
November 24, 2022

exim4 vulnerability
==========================================================================

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

- Ubuntu 22.10
- Ubuntu 22.04 LTS
- Ubuntu 20.04 LTS
- Ubuntu 18.04 LTS

Summary:

Exim could be made to crash or run programs if it processed specially
crafted regular expressions.

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

Details:

It was discovered that Exim incorrectly handled certain regular
expressions. An attacker could use this issue to cause Exim to crash,
resulting in a denial of service, or possibly execute arbitrary code.

Update instructions:

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

Ubuntu 22.10:
exim4-base 4.96-3ubuntu1.1
exim4-daemon-heavy 4.96-3ubuntu1.1
exim4-daemon-light 4.96-3ubuntu1.1

Ubuntu 22.04 LTS:
exim4-base 4.95-4ubuntu2.2
exim4-daemon-heavy 4.95-4ubuntu2.2
exim4-daemon-light 4.95-4ubuntu2.2

Ubuntu 20.04 LTS:
exim4-base 4.93-13ubuntu1.7
exim4-daemon-heavy 4.93-13ubuntu1.7
exim4-daemon-light 4.93-13ubuntu1.7

Ubuntu 18.04 LTS:
exim4-base 4.90.1-1ubuntu1.10
exim4-daemon-heavy 4.90.1-1ubuntu1.10
exim4-daemon-light 4.90.1-1ubuntu1.10

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

References:
https://ubuntu.com/security/notices/USN-5741-1
CVE-2022-3559

Package Information:
https://launchpad.net/ubuntu/+source/exim4/4.96-3ubuntu1.1
https://launchpad.net/ubuntu/+source/exim4/4.95-4ubuntu2.2
https://launchpad.net/ubuntu/+source/exim4/4.93-13ubuntu1.7
https://launchpad.net/ubuntu/+source/exim4/4.90.1-1ubuntu1.10