Missing input validation of host names returned by Domain Name Servers
in the c-ares library can lead to output of wrong hostnames (leading to
Domain Hijacking).

The Common Vulnerabilities and Exposures (CVE) project has assigned the
name CVE-2021-3672 to this issue.

References: https://c-ares.haxx.se/adv_20210810.html
Signed-off-by: Petr Štetiar <ynezz@true.cz>