The Runtime Toolkit in CODESYS Runtime System 2.3.x and 2.4.x does not require authentication, which allows remote attackers to execute commands via the command-line interface in the TCP listener service or transfer files via requests to the TCP listener service.
https://www.cisa.gov/news-events/ics-advisories/icsa-14-084-01
https://www.cisa.gov/news-events/ics-advisories/icsa-13-011-01
https://us.codesys.com/ecosystem/security/
http://www.us-cert.gov/control_systems/pdf/ICSA-13-011-01.pdf