Cisco Secure Firewall ASA/FTD SSL VPN Remote DoS Vulnerability (CVE-2026-20349)

Cisco Secure Firewall Adaptive Security Appliance and Secure Firewall Threat Defense Software Remote Access SSL VPN Denial of Service Vulnerability Vulnerability Overview CVE ID: CVE-2026-20349 CVSS Score: Base 8.8 Publication Date: August 11, 2026 Vulnerability Type: Denial of Service (DoS) in Remote Access SSL VPN service Vulnerability Description: This vulnerability is caused by insufficient input validation when handling HTTP requests. An attacker can exploit this vulnerability by sending a crafted HTTP request to the Remote Access SSL VPN service on an affected device, causing the device to unexpectedly reload and resulting in a Denial of Service (DoS) condition. Affected Products Affected Products: - Cisco Secure Firewall ASA Software - Cisco Secure Firewall Threat Defense (FTD) Software - Remote Access SSL VPN feature with specific configurations - SSL VPN - Zero Trust Network Access Remediation Fixed Versions: - Cisco Secure Firewall ASA Software: - 9.16: 89.16.4.50 - 9.18: 89.18.4.50 - 9.20: 9.20.4.235 - 9.22: 9.22.3.191 - 9.23: 9.23.1.211 - 9.24: 9.24.1.221 - Cisco Secure Firewall FTD Software: - 7.0: Cisco_FTD_Hotfix_GC-7.0.9.1-1.sh.REL.tar, Cisco_FTD_SSP_FP1K_Hotfix_GC-7.0.9.1-1.sh.REL.tar, Cisco_FTD_SSP_FP2K_Hotfix_GC-7.0.9.1-1.sh.REL.tar, Cisco_FTD_SSP_Hotfix_GC-7.0.9.1-1.sh.REL.tar - 7.2: Cisco_FTD_Hotfix_HM-7.2.11.1-2.sh.REL.tar, Cisco_FTD_SSP_FP1K_Hotfix_HM-7.2.11.1-2.sh.REL.tar, Cisco_FTD_SSP_FP2K_Hotfix_HM-7.2.11.1-2.sh.REL.tar, Cisco_FTD_SSP_FP3K_Hotfix_HM-7.2.11.1-2.sh.REL.tar, Cisco_FTD_SSP_Hotfix_HM-7.2.11.1-2.sh.REL.tar - 7.4: Cisco_FTD_Hotfix_HK-7.4.7.1-1.sh.REL.tar, Cisco_FTD_SSP_FP1K_Hotfix_HK-7.4.7.1-1.sh.REL.tar, Cisco_FTD_SSP_FP2K_Hotfix_HK-7.4.7.1-1.sh.REL.tar, Cisco_FTD_SSP_FP3K_Hotfix_HK-7.4.7.1-1.sh.REL.tar, Cisco_FTD_SSP_Hotfix_HK-7.4.7.1-1.sh.REL.tar, Cisco_Secure_FW_TD_4200_Hotfix_HK-7.4.7.1-2.sh.REL.tar - 7.5: Cisco_FTD_Hotfix_DD-7.5.4.1-2.sh.REL.tar, Cisco_FTD_SSP_FP1K_Hotfix_DD-7.5.4.1-2.sh.REL.tar, Cisco_FTD_SSP_FP2K_Hotfix_DD-7.5.4.1-2.sh.REL.tar, Cisco_FTD_SSP_Hotfix_DD-7.5.4.1-2.sh.REL.tar, Cisco_Secure_FW_TD_4200_Hotfix_DD-7.5.4.1-2.sh.REL.tar - 7.7: Cisco_FTD_Hotfix_AN-7.7.11.1-2.sh.REL.tar, Cisco_FTD_SSP_FP1K_Hotfix_AN-7.7.11.1-2.sh.REL.tar, Cisco_FTD_SSP_FP2K_Hotfix_AN-7.7.11.1-2.sh.REL.tar, Cisco_FTD_SSP_Hotfix_AN-7.7.11.1-2.sh.REL.tar, Cisco_Secure_FW_TD_1200_Hotfix_AN-7.7.11.1-2.sh.REL.tar, Cisco_Secure_FW_TD_4200_Hotfix_AN-7.7.11.1-2.sh.REL.tar - 10.0: Cisco_FTD_Hotfix_S-10.0.0.1-2.sh.REL.tar, Cisco_FTD_SSP_FP1K_Hotfix_S-10.0.0.1-2.sh.REL.tar, Cisco_FTD_SSP_FP2K_Hotfix_S-10.0.0.1-2.sh.REL.tar, Cisco_FTD_SSP_Hotfix_S-10.0.0.1-2.sh.REL.tar, Cisco_Secure_FW_TD_200_Hotfix_R-10.0.0.1-2.sh.REL.tar, Cisco_Secure_FW_TD_1200_Hotfix_S-10.0.0.1-2.sh.REL.tar, Cisco_Secure_FW_TD_4200_Hotfix_S-10.0.0.1-2.sh.REL.tar, Cisco_Secure_FW_TD_8100_Hotfix_S-10.0.0.1-2.sh.REL.tar Additional Information Workarounds: No known workarounds Product Confirmation: Only the listed products are known to be affected by this vulnerability Source: Discovered through internal security testing and reported to Cisco by Valero Brussani Exploitation Status: In August 2026, the Cisco Product Security Incident Response Team (PSIRT) became aware of active exploitation of this vulnerability.

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Cisco Secure Firewall ASA/FTD SSL VPN Remote DoS Vulnerability (CVE-2026-20349)