========================================================================== Ubuntu Security Notice USN-8382-1 June 03, 2026
exim4 vulnerabilities
==========================================================================
A security issue affects these releases of Ubuntu and its derivatives:
- Ubuntu 20.04 LTS
- Ubuntu 18.04 LTS
- Ubuntu 16.04 LTS
- Ubuntu 14.04 LTS
Summary:
Several security issues were fixed in Exim.
Software Description:
- exim4: Exim is a mail transport agent
Details:
Timo Longin discovered that Exim incorrectly handled certain SMTP messages
in PIPELINING/CHUNKING configurations. A remote attacker could possibly use
this issue to perform SMTP smuggling. This issue only affected Ubuntu
14.04 LTS. (CVE-2023-51766)
It was discovered that Exim incorrectly handled certain malformed JSON
data in headers. A remote attacker could possibly use this issue to crash
Exim, resulting in a denial of service, or execute arbitrary code. This
issue only affected Ubuntu 20.04 LTS. (CVE-2026-40685)
It was discovered that Exim incorrectly handled certain malformed UTF-8
headers. A remote attacker could possibly use this issue to obtain
sensitive information. This issue only affected Ubuntu 20.04 LTS.
(CVE-2026-40686)
It was discovered that Exim incorrectly handled certain SPA resources.
A remote attacker could possibly use this issue to crash Exim, resulting in
a denial of service, or obtain sensitive information. This issue only
affected Ubuntu 20.04 LTS. (CVE-2026-40687)
It was discovered that Exim incorrectly handled certain CHUNKING
transfers in some GnuTLS configurations. A remote attacker could possibly
use this issue to crash Exim, resulting in a denial of service, or execute
arbitrary code. This issue only affected Ubuntu 20.04 LTS. (CVE-2026-45185)
Warisjeet Singh discovered that Exim incorrectly handled certain proxy
connections in builds with proxy support enabled. A remote attacker could
possibly use this issue to obtain sensitive information. This issue only
affected Ubuntu 16.04 LTS, Ubuntu 18.04 LTS, and Ubuntu 20.04 LTS.
(CVE-2026-48840)
Update instructions:
The problem can be corrected by updating your system to the following
package versions:
Ubuntu 20.04 LTS
exim4 4.93-13ubuntu1.12+esm1
Available with Ubuntu Pro
exim4-base 4.93-13ubuntu1.12+esm1
Available with Ubuntu Pro
exim4-daemon-heavy 4.93-13ubuntu1.12+esm1
Available with Ubuntu Pro
exim4-daemon-light 4.93-13ubuntu1.12+esm1
Available with Ubuntu Pro
exim4-dev 4.93-13ubuntu1.12+esm1
Available with Ubuntu Pro
eximon4 4.93-13ubuntu1.12+esm1
Available with Ubuntu Pro
Ubuntu 18.04 LTS
exim4 4.90.1-1ubuntu1.10+esm6
Available with Ubuntu Pro
exim4-base 4.90.1-1ubuntu1.10+esm6
Available with Ubuntu Pro
exim4-daemon-heavy 4.90.1-1ubuntu1.10+esm6
Available with Ubuntu Pro
exim4-daemon-light 4.90.1-1ubuntu1.10+esm6
Available with Ubuntu Pro
exim4-dev 4.90.1-1ubuntu1.10+esm6
Available with Ubuntu Pro
eximon4 4.90.1-1ubuntu1.10+esm6
Available with Ubuntu Pro
Ubuntu 16.04 LTS
exim4 4.86.2-2ubuntu2.6+esm9
Available with Ubuntu Pro
exim4-base 4.86.2-2ubuntu2.6+esm9
Available with Ubuntu Pro
exim4-daemon-heavy 4.86.2-2ubuntu2.6+esm9
Available with Ubuntu Pro
exim4-daemon-light 4.86.2-2ubuntu2.6+esm9
Available with Ubuntu Pro
exim4-dev 4.86.2-2ubuntu2.6+esm9
Available with Ubuntu Pro
eximon4 4.86.2-2ubuntu2.6+esm9
Available with Ubuntu Pro
Ubuntu 14.04 LTS
exim4 4.82-3ubuntu2.4+esm9
Available with Ubuntu Pro
exim4-base 4.82-3ubuntu2.4+esm9
Available with Ubuntu Pro
exim4-daemon-heavy 4.82-3ubuntu2.4+esm9
Available with Ubuntu Pro
exim4-daemon-light 4.82-3ubuntu2.4+esm9
Available with Ubuntu Pro
exim4-dev 4.82-3ubuntu2.4+esm9
Available with Ubuntu Pro
eximon4 4.82-3ubuntu2.4+esm9
Available with Ubuntu Pro
In general, a standard system update will make all the necessary changes.
References:
https://ubuntu.com/security/notices/USN-8382-1
CVE-2023-51766, CVE-2026-40685, CVE-2026-40686, CVE-2026-40687,
CVE-2026-45185, CVE-2026-48840
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