USN-3353-1: Heimdal vulnerability

14 July 2017

heimdal vulnerability

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

  • Ubuntu 17.04
  • Ubuntu 16.10
  • Ubuntu 16.04 LTS
  • Ubuntu 14.04 LTS


Heimdal could allow unintended access to network services.

Software Description

  • heimdal - Heimdal Kerberos Network Authentication Protocol


Jeffrey Altman, Viktor Dukhovni, and Nicolas Williams discovered that Heimdal clients incorrectly trusted unauthenticated portions of Kerberos tickets. A remote attacker could use this to impersonate trusted network services or perform other attacks.

Update instructions

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

Ubuntu 17.04
libkrb5-26-heimdal - 7.1.0+dfsg-9ubuntu1.1
Ubuntu 16.10
libkrb5-26-heimdal - 1.7~git20150920+dfsg-4ubuntu1.16.10.1
Ubuntu 16.04 LTS
libkrb5-26-heimdal - 1.7~git20150920+dfsg-4ubuntu1.16.04.1
Ubuntu 14.04 LTS
libkrb5-26-heimdal - 1.6~git20131207+dfsg-1ubuntu1.2

To update your system, please follow these instructions:

After a standard system update you need to restart any applications using Heimdal libraries to make all the necessary changes.