Sensys Networks VSN240-F and VSN240-T sensors VDS before 2.10.1 and TrafficDOT before 2.10.3 do not use encryption, which allows remote attackers to interfere with traffic control by replaying transmissions on a wireless network.
https://www.cisa.gov/news-events/ics-advisories/icsa-14-247-01a
https://ics-cert.us-cert.gov/advisories/ICSA-14-247-01