CVE-2025-20135 Cisco Adaptive Security Appliance and Firepower Threat Defense Software DHCP Denial of Service Vulnerability
An unauthenticated adjacent attacker can cause a denial of service by exhausting memory via crafted DHCPv4 packets on Cisco ASA and FTD devices.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2025-20135?
CVE-2025-20135 is a medium-severity denial of service vulnerability in Cisco Adaptive Security Appliance (ASA) Software, published on 14 Aug 2025. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
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 exhaust available memory. This vulnerability is due to improper validation of incoming DHCP packets. An attacker could exploit this vulnerability by repeatedly sending crafted DHCPv4 packets to an affected device. A successful exploit could allow the attacker to exhaust available memory, which would affect availability of services and prevent new processes from starting, resulting in a Denial of Service (DoS) condition that would require a manual reboot. Note: On Cisco Secure FTD Software, this vulnerability does not affect management interfaces.
Weakness: CWE-401
Which versions are affected by CVE-2025-20135?
How do I fix CVE-2025-20135?
No fix has been published for CVE-2025-20135 yet. Limit exposure of the affected software until one is available.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2025-20135 being exploited?
There is no known exploitation of CVE-2025-20135 in the wild and no public exploit code.
Sources
Also known as GHSA-j8qj-frmg-5g7v.