Heap-based buffer overflow in Progea Movicon / PowerHMI 11.2.1085 and earlier allows remote attackers to cause a denial of service (crash) and possibly execute arbitrary code via a negative Content-Length field.
https://exchange.xforce.ibmcloud.com/vulnerabilities/69787
http://www.us-cert.gov/control_systems/pdf/ICS-ALERT-11-256-01.pdf