CVE-2026-20349
Cisco Secure Firewall Adaptive Security Appliance and Secure Firewall Threat Defense Software Remote Access SSL VPN Denial of Service Vulnerability
Cisco·Secure Firewall Adaptive Security Appliance (ASA) and Secure Firewall Threat Defense (FTD)
- Added
- Aug 11, 2026
- Fix due
- Aug 14, 2026
- Ransomware
- Not known
- Published
- Aug 11, 2026
- Updated
- Sep 16, 2026
- First covered
- Aug 12, 2026
- Latest story
- 2 weeks ago
Summary
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.
CWE-244Improper Clearing of Heap Memory Before Release ('Heap Inspection')
Attack profile
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:HCISA required action
Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.
Affected products
- Cisco Secure Firewall Adaptive Security Appliance (ASA) Software9.16.19.16.1.289.16.29.16.2.3
- Cisco Secure Firewall Threat Defense (FTD) Software7.0.07.0.0.17.0.17.0.1.1