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CVE-2026-20349: Cisco Secure Firewall Adaptive Security Appliance (ASA) and Secure Firewall Threat Defense (FTD) Heap Inspection Vulnerability
CVE-2026-20349: high vulnerability affecting Secure Firewall Adaptive Security Appliance (ASA) and Secure Firewall Threat Defense (FTD). Check CVSS, KEV.
- CVSS
- 8.6 HIGH
- EPSS
- 81.58%
- Known exploited
- yes
- Product
- Secure Firewall Adaptive Security Appliance (ASA) and Secure Firewall Threat Defense (FTD)
What is known
A vulnerability in the Remote Access SSL VPN service 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 insufficient error checking when processing HTTP requests. An attacker could exploit this vulnerability by sending a crafted HTTP request to the Remote Access SSL VPN service on an affected device. A successful exploit could allow the attacker to cause the affected device to reload, resulting in a DoS condition.
Business impact
Successful exploitation of CVE-2026-20349, a high vulnerability (CVSS 8.6) affecting Secure Firewall Adaptive Security Appliance (ASA) and Secure Firewall Threat Defense (FTD), may affect the confidentiality, integrity or availability of the vulnerable environment. The exact impact depends on the installed version, exposed interfaces and deployment configuration. CISA lists this vulnerability in the Known Exploited Vulnerabilities catalog, so exposed systems should be treated as a priority.
Recommended administrator action
Confirm whether Secure Firewall Adaptive Security Appliance (ASA) and Secure Firewall Threat Defense (FTD) is present and compare installed versions with the vendor advisory and NVD record. Apply the vendor patch or documented mitigation; until remediation is complete, reduce exposure of affected interfaces, review relevant logs and monitor for indicators of exploitation. Where applicable, include the CISA KEV remediation due date of 2026-08-14 in the change plan. DataHouse can support version verification, managed patching, network exposure reduction, log review and backup validation for dedicated, cloud and colocated environments.