USN-3434-1: Libidn vulnerability

2 October 2017

libidn vulnerability

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

  • Ubuntu 17.04
  • Ubuntu 16.04 LTS
  • Ubuntu 14.04 LTS


Libidn could be made to crash or run programs if it processed specially crafted input.

Software Description

  • libidn - implementation of IETF IDN specifications


It was discovered that Libidn incorrectly handled decoding certain digits. A remote attacker could use this issue to cause Libidn to crash, resulting in a denial of service, or possibly execute arbitrary code.

Update instructions

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

Ubuntu 17.04
libidn11 - 1.33-1ubuntu0.1
Ubuntu 16.04 LTS
libidn11 - 1.32-3ubuntu1.2
Ubuntu 14.04 LTS
libidn11 - 1.28-1ubuntu2.2

To update your system, please follow these instructions:

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