CVE-2018-15399

CVE-2018-15399 is a denial-of-service vulnerability in Cisco Adaptive Security Appliance (ASA) Software and Firepower Threat Defense (FTD) Software, stemming from a missing boundary check in the TCP syslog module. An unauthenticated, remote attacker can exploit this by establishing a man-in-the-middle position to maliciously modify TCP headers, exhausting device buffers. This medium-severity vulnerability (CVSS 6.8) requires high attack complexity due to the man-in-the-middle prerequisite, but can lead to a complete denial of service for all TCP-based features. There is no evidence of active exploitation, public exploit code, or significant community discussion surrounding this CVE.