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Ubuntu Exim Security Advisory 8382-1 CVE-2023-51766 CVE-2026-40685

ubuntu
Calendar Grey June 3, 2026
Dist Ubuntu Esm H88
Exim vulnerabilities fixed in Ubuntu, affecting multiple releases and enhancing security against remote attacks. Read more.
Several security issues were fixed in Exim.

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...

Read the Full Advisory

Topics%20covered

Topics Covered

security advisory denial of service remote access exim Ubuntu SMTP

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

Severity
important
Lowest
Low
Medium
High
Critical

Ubuntu Security Notice USN-8382-1

Topics%20covered

Topics Covered

security advisory denial of service remote access exim Ubuntu SMTP

Package Information

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