An exploitable double free vulnerability exists in the iocheckd service "I/O-Check" functionality of WAGO PFC 200. A specially crafted XML cache file written to a specific location on the device can cause a heap pointer to be freed twice, resulting in a denial of service and potentially code execution. An attacker can send a specially crafted packet to trigger the parsing of this cache file.
https://talosintelligence.com/vulnerability_reports/TALOS-2019-0965