USN-1130-1: Exim vulnerability

10 May 2011

exim4 vulnerability

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

  • Ubuntu 11.04
  • Ubuntu 10.10
  • Ubuntu 10.04 LTS

Summary

Exim could be made to run arbitrary code under some conditions.

Software Description

  • exim4 - Exim mail transfer agent

Details

It was discovered that the Exim daemon did not correctly handle format strings in DKIM headers. An unauthenticated remote attacker could send specially crafted email to run arbitrary code as the Exim user. The default compiler options for affected releases reduces the vulnerability to a denial of service under most conditions.

Update instructions

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

Ubuntu 11.04
exim4-daemon-custom - 4.74-1ubuntu1.1
exim4-daemon-heavy - 4.74-1ubuntu1.1
exim4-daemon-light - 4.74-1ubuntu1.1
Ubuntu 10.10
exim4-daemon-custom - 4.72-1ubuntu1.2
exim4-daemon-heavy - 4.72-1ubuntu1.2
exim4-daemon-light - 4.72-1ubuntu1.2
Ubuntu 10.04 LTS
exim4-daemon-custom - 4.71-3ubuntu1.2
exim4-daemon-heavy - 4.71-3ubuntu1.2
exim4-daemon-light - 4.71-3ubuntu1.2

To update your system, please follow these instructions: https://wiki.ubuntu.com/Security/Upgrades.

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

References