CVE-2026-20349
Cisco Secure Firewall Adaptive Security Appliance (ASA) and Secure Firewall Threat Defense (FTD) Heap Inspection Vulnerability
IN CISA KEV
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.
- Vendor
- Cisco
- Product
- Secure Firewall Adaptive Security Appliance (ASA) and Secure Firewall Threat Defense (FTD)
- CVSS 3.1
- 8.6 (high), scored by psirt@cisco.comCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
- CWE
- CWE-244
- Published
- 2026-08-11
- NVD modified
- 2026-09-16
- NVD status
- Analyzed
CISA KEV
- Date added
- 2026-08-11
- Due date
- 2026-08-14
- Ransomware use
- Unknown
- 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.
EPSS
1.01% chance of exploitation in the next 30 days (percentile 62nd)
FIRST EPSS, updated 17 Oct 2026. About EPSS
CVSS is severity, EPSS is likelihood, KEV means already exploited. EPSS is a statistical probability, not a certainty: a low score does not make a bug safe, and a high one does not prove it is being exploited.
References
- sec.cloudapps.cisco.com (Vendor Advisory)
- www.cisa.gov (US Government Resource)
Data last updated 18 Oct 2026. Sources: NVD API 2.0, CISA KEV catalog, FIRST EPSS. Links: NVD, CISA KEV. Metadata only. ThreatWire does not host exploit code.