A critical vulnerability (CVE-2018-6789) recently discovered in Exim, a mail transfer agent used to relay emails from senders to recipients, affects 56 percent of all email servers worldwide. If exploited, this vulnerability creates a buffer overflow condition that can allow a remote threat actor to execute code prior to being authenticated by the affected Exim email server. This vulnerability affects all versions of Exim prior to the patched version 4.90.1. Using Shodan, a publicly available internet-of-things (IoT) search engine, NJCCIC analysts determined that nearly 64,000 email servers within New Jersey run Exim and, out of those, only 829 are running the patched version. The NJCCIC recommends all administrators of email servers running Exim review the Exim security advisory and update to version 4.90.1 as soon as possible. More information about the Exim vulnerability is also available on the Devcore website.