Vulnerability in Cisco Adaptive Security Appliance (Asa) Software
CVE-2025-20136
A vulnerability in the function that performs IPv4 and IPv6 Network Address Translation (NAT) DNS inspection for Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and Cisco Secure Firewall Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause the device to reload unexpectedly, resulting in a denial of service (DoS) condition. This vulnerability is due to an infinite loop condition that occurs when a Cisco Secure ASA or Cisco Secure FTD device processes DNS packets with DNS inspection enabled and the device is configured for NAT44, NAT64, or NAT46. An attacker could exploit this vulnerability by sending crafted DNS packets that match a static NAT rule with DNS inspection enabled through an affected device. A successful exploit could allow the attacker to create an infinite loop and cause the device to reload, resulting in a DoS condition.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 8.6 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H.
EPSS exploit prediction
EPSS: 0.006 (49.5th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 50th percentile — 49.5% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.006 · newest: 0.006 · 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-2025-20136?
- CVE-2025-20136 is a high-severity vulnerability in Cisco Adaptive Security Appliance (Asa) Software, classified under Loop with Unreachable Exit Condition (Infinite Loop). CVSS score: 8.6/10. Published 2025-08-14.
- How severe is CVE-2025-20136?
- High severity. CVSS v3 base score is 8.6 out of 10.