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[USN-8228-1] Exim vulnerabilities

Posted on 04 May 2026
Ubuntu Security

==========================================================================Ubuntu Security Notice USN-8228-1
May 04, 2026

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

- Ubuntu 26.04 LTS
- Ubuntu 25.10
- Ubuntu 24.04 LTS
- Ubuntu 22.04 LTS

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 parsing malformed JSON
in message headers. A remote attacker could possibly use this issue to
execute arbitrary code. (CVE-2026-40685)

It was discovered that Exim incorrectly handled processing of UTF-8
trailing characters. A remote attacker could possibly use this issue to
obtain sensitive information. (CVE-2026-40686)

It was discovered that Exim incorrectly handled SPA authenticator input.
An authenticated user could possibly use this issue to execute arbitrary
code. (CVE-2026-40687)

Update instructions:

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

Ubuntu 26.04 LTS
exim4 4.99.1-1ubuntu1.1
exim4-base 4.99.1-1ubuntu1.1
eximon4 4.99.1-1ubuntu1.1

Ubuntu 25.10
exim4 4.98.2-1ubuntu2.1
exim4-base 4.98.2-1ubuntu2.1
eximon4 4.98.2-1ubuntu2.1

Ubuntu 24.04 LTS
exim4 4.97-4ubuntu4.4
exim4-base 4.97-4ubuntu4.4
eximon4 4.97-4ubuntu4.4

Ubuntu 22.04 LTS
exim4 4.95-4ubuntu2.7
exim4-base 4.95-4ubuntu2.7
eximon4 4.95-4ubuntu2.7

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

References:
https://ubuntu.com/security/notices/USN-8228-1
CVE-2026-40685, CVE-2026-40686, CVE-2026-40687

Package Information:
https://launchpad.net/ubuntu/+source/exim4/4.99.1-1ubuntu1.1
https://launchpad.net/ubuntu/+source/exim4/4.98.2-1ubuntu2.1
https://launchpad.net/ubuntu/+source/exim4/4.97-4ubuntu4.4
https://launchpad.net/ubuntu/+source/exim4/4.95-4ubuntu2.7

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