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CVE-2026-20349

HIGH 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.

Published: Aug 11, 2026 Modified: Aug 12, 2026
CWE-244

CVSS Metrics

CVSSv3
Attack Vector: NETWORK Attack Complexity: LOW Privileges Required: NONE User Interaction: NONE Scope: CHANGED Confidentiality Impact: NONE Integrity Impact: NONE Availability Impact: HIGH

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H

Affected Products (197)

Vendor Product Version
cisco adaptive_security_appliance_software 9.16.1
cisco adaptive_security_appliance_software 9.16.1.28
cisco adaptive_security_appliance_software 9.16.2
cisco adaptive_security_appliance_software 9.16.2.3
cisco adaptive_security_appliance_software 9.16.2.7
cisco adaptive_security_appliance_software 9.16.2.11
cisco adaptive_security_appliance_software 9.16.2.13
cisco adaptive_security_appliance_software 9.16.2.14
cisco adaptive_security_appliance_software 9.16.3
cisco adaptive_security_appliance_software 9.16.3.3
cisco adaptive_security_appliance_software 9.16.3.14
cisco adaptive_security_appliance_software 9.16.3.15
cisco adaptive_security_appliance_software 9.16.3.19
cisco adaptive_security_appliance_software 9.16.3.23
cisco adaptive_security_appliance_software 9.16.4
cisco adaptive_security_appliance_software 9.16.4.9
cisco adaptive_security_appliance_software 9.16.4.14
cisco adaptive_security_appliance_software 9.16.4.19
cisco adaptive_security_appliance_software 9.16.4.27
cisco adaptive_security_appliance_software 9.16.4.38

…and 177 more

GitHub Security Advisory GHSA-8x4j-5v9x-9frv

A vulnerability in the Remote Access SSL VPN service for Cisco Secure Firewall Adaptive Security...

Risk Scores

CVSS Score 8.6 / 10
EPSS Score 1.02%

Top 40% most likely to be exploited

Threat Score 64.7 / 100

CISA Known Exploited

Date Added: 2026-08-11
Due Date: 2026-08-14
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.

Data Sources

NVD CISA KEV EPSS GitHub