Teltonika’s Remote Management System versions prior to 4.10.0 contain a virtual private network (VPN) hub feature for cross-device communication that uses OpenVPN. It connects new devices in a manner that allows the new device to communicate with all Teltonika devices connected to the VPN. The OpenVPN server also allows users to route through it. An attacker could route a connection to a remote server through the OpenVPN server, enabling them to scan and access data from other Teltonika devices connected to the VPN.
https://www.cisa.gov/news-events/ics-advisories/icsa-23-131-08