Cisco warns that a zero-day vulnerability (CVE-2023-20269) in Adaptive Security Appliance (ASA) and Cisco Firepower Threat Defense (FTD) is actively exploited by ransomware groups to gain initial access to corporate networks.

An unauthenticated, remote attacker can exploit the vulnerability to conduct a brute force attack in an attempt to identify valid username and password combinations or an authenticated, remote attacker to establish a clientless SSL VPN session with an unauthorized user.