Several security issues were fixed in Libidn.
Thijs Alkemade, Gustavo Grieco, Daniel Stenberg, and Nikos Mavrogiannopoulos discovered that Libidn incorrectly handled invalid UTF-8 characters. A remote attacker could use this issue to cause Libidn to crash, resulting in a denial of service, or possibly disclose sensitive memory. This issue only applied to Ubuntu 12.04 LTS and Ubuntu 14.04 LTS. (CVE-2015-2059)
24 August 2016
A security issue affects these releases of Ubuntu and its derivatives:
Several security issues were fixed in Libidn.
Thijs Alkemade, Gustavo Grieco, Daniel Stenberg, and Nikos Mavrogiannopoulos discovered that Libidn incorrectly handled invalid UTF-8 characters. A remote attacker could use this issue to cause Libidn to crash, resulting in a denial of service, or possibly disclose sensitive memory. This issue only applied to Ubuntu 12.04 LTS and Ubuntu 14.04 LTS. (CVE-2015-2059)
Hanno Böck discovered that Libidn incorrectly handled certain input. A remote attacker could possibly use this issue to cause Libidn to crash, resulting in a denial of service. (CVE-2015-8948, CVE-2016-6262, CVE-2016-6261, CVE-2016-6263)
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.
In general, a standard system update will make all the necessary changes.