CVE-2025-20134 Denial of service in Cisco Adaptive Security Appliance (ASA) Software
Remote attackers can cause Cisco ASA and FTD devices to reload by sending crafted DNS packets, resulting in a denial of service.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2025-20134?
CVE-2025-20134 is a high-severity denial of service vulnerability in Cisco Adaptive Security Appliance (ASA) Software, published on 14 Aug 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
A vulnerability in the certificate processing of 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 improper parsing of SSL/TLS certificates. An attacker could exploit this vulnerability by sending crafted DNS packets that match a static Network Address Translation (NAT) rule with DNS inspection enabled through an affected device. A successful exploit could allow the attacker to cause the device to reload, resulting in a DoS condition.
Weakness: CWE-415
Which versions are affected by CVE-2025-20134?
How do I fix CVE-2025-20134?
No fix has been published for CVE-2025-20134 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-2025-20134 being exploited?
There is no known exploitation of CVE-2025-20134 in the wild and no public exploit code.
Sources
Also known as GHSA-wmcm-x4v8-vf3r.