Heimdal could allow unintended access to network services.
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.
14 July 2017
A security issue affects these releases of Ubuntu and its derivatives:
Heimdal could allow unintended access to network services.
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.
The problem can be corrected by updating your system to the following package versions:
To update your system, please follow these instructions: https://wiki.ubuntu.com/Security/Upgrades.
After a standard system update you need to restart any applications using Heimdal libraries to make all the necessary changes.