Vulnerability in Cisco Adaptive Security Appliance (Asa) Software
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 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.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 4.3 (Medium). Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L.
EPSS exploit prediction
EPSS: 0.002 (8.7th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 9th percentile — 8.7% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.002 · newest: 0.002 · change: 0.000
Affected products
- Cisco Adaptive Security Appliance (Asa) Software — versions 9.12.3, 9.8.3, 9.12.1
- Cisco Firepower Threat Defense Software — versions 6.2.3.14, 6.4.0.1, 6.2.3.7
Weakness classification (CWE)
References
Frequently asked questions
- What is CVE-2025-20135?
- CVE-2025-20135 is a medium-severity vulnerability in Cisco Adaptive Security Appliance (Asa) Software, classified under Missing Release of Memory after Effective Lifetime. CVSS score: 4.3/10. Published 2025-08-14.
- How severe is CVE-2025-20135?
- Medium severity. CVSS v3 base score is 4.3 out of 10.