Improper certificate validation vulnerability in OpenVPN client in Synology DiskStation Manager (DSM) before 6.2.3-25426-2 allows man-in-the-middle attackers to spoof servers and obtain sensitive information via a crafted certificate.
https://www.talosintelligence.com/vulnerability_reports/TALOS-2020-1058
https://www.synology.com/security/advisory/Synology_SA_20_18