Memory Exhaustion Vulnerability in Cisco Secure Firewall ASA and FTD Software

CVE-2025-20135

What is CVE-2025-20135?

A vulnerability in the DHCP client functionality of Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and Cisco Secure Firewall Threat Defense (FTD) Software could allow an unauthenticated, adjacent attacker to exploit improper validation of incoming DHCP packets. By sending specifically crafted DHCPv4 packets repeatedly to an affected device, an attacker could exhaust the available memory. This condition would impact the availability of services, preventing new processes from starting, and resulting in a Denial of Service (DoS) situation that necessitates a manual reboot of the affected device.

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