USN-3395-1: c-ares vulnerability

17 August 2017

c-ares vulnerability

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

  • Ubuntu 17.04
  • Ubuntu 16.04 LTS
  • Ubuntu 14.04 LTS


c-ares could be made to crash if it received specially crafted network traffic.

Software Description

  • c-ares - library for asynchronous name resolution


It was discovered that c-ares incorrectly handled certain NAPTR responses. A remote attacker could possibly use this issue to cause applications using c-ares to crash, resulting in a denial of service.

Update instructions

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

Ubuntu 17.04
libc-ares2 - 1.12.0-1ubuntu0.1
Ubuntu 16.04 LTS
libc-ares2 - 1.10.0-3ubuntu0.2
Ubuntu 14.04 LTS
libc-ares2 - 1.10.0-2ubuntu0.2

To update your system, please follow these instructions:

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