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Ubuntu Security Notice USN-3353-3
July 24, 2017

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

    Ubuntu 12.04 LTS

Summary

Heimdal could allow unintended access to network services.
Software description

    heimdal - Heimdal Kerberos Network Authentication Protocol

Details

USN-3353-1 fixed a vulnerability in Heimdal. This update provides
the corresponding updade for Ubuntu 12.04 ESM.

Original advisory details:

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 version:

Ubuntu 12.04 LTS:
    libkrb5-26-heimdal 1.6~git20120311.dfsg.1-2ubuntu0.2 

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.

References

https://www.ubuntu.com/usn/usn-3353-3
https://www.ubuntu.com/usn/usn-3353-1
CVE-2017-11103