USN-3493-1: Exim vulnerability

27 November 2017

exim4 vulnerability

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

  • Ubuntu 17.10
  • Ubuntu 17.04


Exim could be made to crash or run programs if it received specially crafted network traffic.

Software Description

  • exim4 - Exim is a mail transport agent


It was discovered that Exim incorrectly handled memory in the ESMTP CHUNKING extension. A remote attacker could use this issue to cause Exim to crash, resulting in a denial of service, or possibly execute arbitrary code. The default compiler options for affected releases should reduce the vulnerability to a denial of service.

Update instructions

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

Ubuntu 17.10
exim4-daemon-heavy - 4.89-5ubuntu1.1
exim4-daemon-light - 4.89-5ubuntu1.1
Ubuntu 17.04
exim4-daemon-heavy - 4.88-5ubuntu1.2
exim4-daemon-light - 4.88-5ubuntu1.2

To update your system, please follow these instructions:

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