Provide references for CVE-2021-4039.
Where can I find more information about CVE-2021-4039?
References are available at: https://www.zyxel.com/support/OS-command-injection-vulnerability-of-NWA1100-NH-access-point.shtml, http://packetstormsecurity.com/files/166752/Zyxel-NWA-1100-NH-Command-Injection.html.