When considering software upgrades, customers are advised to regularly consult the advisories for Cisco products, which are available from the Cisco Security Advisories and Alerts page, to determine exposure and a complete upgrade solution.
In all cases, customers should ensure that the devices to be upgraded contain sufficient memory and confirm that current hardware and software configurations will continue to be supported properly by the new release. If the information is not clear, customers are advised to contact the Cisco Technical Assistance Center (TAC) or their contracted maintenance providers.
At the time of publication, Cisco AsyncOS Software for Cisco Email Security Appliance (ESA) releases 12.5.1 and later contained the fix for this vulnerability.
See the Details section in the bug ID(s) at the top of this advisory for the most complete and current information.