CVE-2025-20135
Cisco Adaptive Security Appliance and Firepower Threat Defense Software DHCP Denial of Service Vulnerability
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
Affected products
| Vendor | Product | Category | Matched by |
|---|---|---|---|
| Cisco | Cisco Adaptive Security Appliance (ASA) Check your version | Firewall / NGFW | cna-assigner |
| Cisco | Cisco Firepower Threat Defense (FTD) Check your version | Firewall / NGFW | cna-assigner |
Vendor-reported products (2)
- Cisco · Cisco Adaptive Security Appliance (ASA) Software
- Cisco · Cisco Firepower Threat Defense Software
Vendor advisory
Cisco Secure Firewall Adaptive Security Appliance and Secure Firewall Threat Defense Software DHCP Denial of Service Vulnerability
Cisco’s rating: Medium (advisory CVSS 4.3) · Published Aug 14, 2025
Bug ID: CSCwm08235
The vendor’s rating applies to the whole advisory and can differ from this CVE’s own CVSS severity. Where this comes from