[USN-5034-2] c-ares vulnerability

========================================================================== Ubuntu Security Notice USN-5034-2 August 10, 2021
c-ares vulnerability ==========================================================================
A security issue affects these releases of Ubuntu and its derivatives:
– Ubuntu 16.04 ESM
Summary:
c-ares could be made to return wrong domains.
Software Description: – c-ares: library for asynchronous name resolution
Details:
USN-5034-1 fixed a vulnerability in c-ares. This update provides the corresponding update for Ubuntu 16.04 ESM.
Original advisory details:
Philipp Jeitner and Haya Shulman discovered that c-ares incorrectly validated certain hostnames returned by DNS servers. A remote attacker could possibly use this issue to perform Domain Hijacking attacks.
Update instructions:
The problem can be corrected by updating your system to the following package versions:
Ubuntu 16.04 ESM: libc-ares2 1.10.0-3ubuntu0.2+esm1
In general, a standard system update will make all the necessary changes.
References: ubuntu.com/security/notices/USN-5034-2 ubuntu.com/security/notices/USN-5034-1 CVE-2021-3672