CVE-2017-3818

CVE-2017-3818 describes a medium-severity vulnerability in the MIME scanner of Cisco AsyncOS Software for Cisco Email Security Appliances (ESA), affecting both virtual and hardware appliances configured with message or content filters for incoming email attachments. An unauthenticated, remote attacker could exploit this flaw to bypass configured user filters, specifically a Malformed MIME Header Filtering Bypass. The CVSSv3 score of 5.8 indicates a network-based attack with low complexity, requiring no user interaction, and resulting in a low impact on integrity. There is no evidence of active exploitation, public exploit code, or significant community discussion surrounding this vulnerability.