A vulnerability in the TLS 1.3 implementation of Cisco Secure Firewall Threat Defense (FTD) Software allows an unauthenticated remote attacker to cause the device to reload unexpectedly, resulting in a denial of service (DoS). The issue arises from improper buffer management during TLS 1.3 connections. Exploitation involves sending a crafted TLS 1.3 packet to a TLS 1.3-enabled listening socket, causing the LINA process to crash and the device to reload either before or after connection authentication.