The results from ten cyber security vulnerability assessments of process control, SCADA and energy management systems, or components of those systems were reviewed to identify common problem areas. The common vulnerabilities ranged from conventional IT security issues to specific weaknesses in control system protocols. In each vulnerability category, relative measures were assigned to the severity of the vulnerability and ease with which an attacker could exploit the vulnerability. Suggested mitigations are identified in each category. Recommended mitigations having the highest impact on reducing vulnerability are listed for asset owners and system vendors.