Improper Authentication vulnerability in Mitsubishi Electric Corporation MELSEC-F Series main modules allows a remote unauthenticated attacker to obtain sequence programs from the product or write malicious sequence programs or improper data in the product without authentication by sending illegitimate messages.
https://www.mitsubishielectric.com/en/psirt/vulnerability/pdf/2023-012_en.pdf
https://www.cisa.gov/news-events/ics-advisories/icsa-23-285-13