An Exim security update has been released for Ubuntu Linux 14.04 LTS, 16.04 LTS, 18.04 LTS, 20.04 LTS, 22.04 LTS, and 23.04.

[USN-6411-1] Exim vulnerabilities

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

exim4 vulnerabilities
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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