Mesh OS before 7.9.1.1 on Tropos wireless mesh routers does not use a sufficient source of entropy for SSH keys, which makes it easier for man-in-the-middle attackers to spoof a device or modify a client-server data stream by leveraging knowledge of a key from a product installation elsewhere.
https://www.cisa.gov/news-events/ics-advisories/icsa-12-297-01
http://www.us-cert.gov/control_systems/pdf/ICSA-12-297-01.pdf