CVE-2026-20349 PUBLISHED

Cisco Secure Firewall Adaptive Security Appliance and Secure Firewall Threat Defense Software Remote Access SSL VPN Denial of Service Vulnerability

Assigner: cisco
Reserved: 08.10.2025 Published: 11.08.2026 Updated: 12.08.2026

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.

Metrics

CVSS 3.1

CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
CVSS Score: 8.6

Attack Vector	Network	Scope	Changed
Attack Complexity	Low	Confidentiality Impact	None
Privileges Required	None	Integrity Impact	None
User Interaction	None	Availability Impact	High

CVSS 3.1

Product Status

Vendor	Cisco
Product	Cisco Secure Firewall Adaptive Security Appliance (ASA) Software
Versions	Default: unknown Version 9.16.1 is affected Version 9.16.1.28 is affected Version 9.16.2 is affected Version 9.16.2.3 is affected Version 9.16.2.7 is affected Version 9.16.2.11 is affected Version 9.16.2.13 is affected Version 9.16.2.14 is affected Version 9.16.3.3 is affected Version 9.16.3 is affected Version 9.16.3.14 is affected Version 9.18.1 is affected Version 9.16.3.15 is affected Version 9.18.1.3 is affected Version 9.18.2 is affected Version 9.16.3.19 is affected Version 9.16.3.23 is affected Version 9.18.2.5 is affected Version 9.16.4 is affected Version 9.18.2.7 is affected Version 9.19.1 is affected Version 9.16.4.9 is affected Version 9.18.2.8 is affected Version 9.16.4.14 is affected Version 9.18.3 is affected Version 9.19.1.5 is affected Version 9.19.1.9 is affected Version 9.18.3.39 is affected Version 9.16.4.19 is affected Version 9.19.1.12 is affected Version 9.18.3.46 is affected Version 9.16.4.27 is affected Version 9.19.1.18 is affected Version 9.18.3.53 is affected Version 9.18.3.55 is affected Version 9.16.4.38 is affected Version 9.16.4.39 is affected Version 9.18.3.56 is affected Version 9.20.1 is affected Version 9.16.4.42 is affected Version 9.19.1.22 is affected Version 9.18.4 is affected Version 9.20.1.5 is affected Version 9.18.4.5 is affected Version 9.19.1.24 is affected Version 9.16.4.48 is affected Version 9.18.4.8 is affected Version 9.20.2 is affected Version 9.19.1.27 is affected Version 9.16.4.55 is affected Version 9.18.4.22 is affected Version 9.20.2.10 is affected Version 9.16.4.57 is affected Version 9.19.1.28 is affected Version 9.18.4.24 is affected Version 9.20.2.21 is affected Version 9.16.4.61 is affected Version 9.19.1.31 is affected Version 9.18.4.29 is affected Version 9.20.2.22 is affected Version 9.16.4.62 is affected Version 9.18.4.34 is affected Version 9.20.3 is affected Version 9.16.4.67 is affected Version 9.16.4.70 is affected Version 9.18.4.40 is affected Version 9.23.1 is affected Version 9.22.1.1 is affected Version 9.16.4.71 is affected Version 9.20.3.4 is affected Version 9.18.4.47 is affected Version 9.20.3.7 is affected Version 9.19.1.37 is affected Version 9.16.4.76 is affected Version 9.20.3.9 is affected Version 9.19.1.38 is affected Version 9.18.4.50 is affected Version 9.22.1.3 is affected Version 9.20.3.10 is affected Version 9.22.1.2 is affected Version 9.18.4.52 is affected Version 9.20.3.13 is affected Version 9.22.1.6 is affected Version 9.18.4.53 is affected Version 9.16.4.82 is affected Version 9.22.2 is affected Version 9.20.3.16 is affected Version 9.19.1.42 is affected Version 9.18.4.57 is affected Version 9.16.4.84 is affected Version 9.23.1.3 is affected Version 9.20.3.20 is affected Version 9.22.2.4 is affected Version 9.23.1.7 is affected Version 9.20.4 is affected Version 9.22.2.9 is affected Version 9.23.1.13 is affected Version 9.20.4.7 is affected Version 9.22.2.13 is affected Version 9.18.4.66 is affected Version 9.20.4.10 is affected Version 9.23.1.19 is affected Version 9.16.4.85 is affected Version 9.22.2.14 is affected Version 9.18.4.67 is affected Version 9.24.1 is affected Version 9.18.4.68 is affected Version 9.23.1.22 is affected Version 9.20.4.14 is affected Version 9.22.2.20 is affected Version 9.18.4.71 is affected Version 9.20.4.19 is affected Version 9.23.1.26 is affected Version 9.16.4.89 is affected Version 9.22.2.32 is affected Version 9.18.4.76 is affected Version 9.22.3 is affected Version 9.24.1.5 is affected Version 9.20.4.22 is affected Version 9.24.1.9 is affected Version 9.20.4.28 is affected Version 9.22.3.5 is affected Version 9.16.4.92 is affected Version 9.18.4.135 is affected Version 9.23.1.195 is affected Version 9.20.4.30 is affected Version 9.24.1.155 is affected Version 9.23.1.32 is affected Version 9.24.1.11 is affected Version 9.20.4.34 is affected Version 9.18.4.82 is affected Version 9.18.4.90 is affected Version 9.20.4.46 is affected

Vendor	Cisco
Product	Cisco Secure Firewall Threat Defense (FTD) Software
Versions	Default: unknown Version 7.0.0 is affected Version 7.0.0.1 is affected Version 7.0.1 is affected Version 7.0.1.1 is affected Version 7.0.2 is affected Version 7.2.0 is affected Version 7.0.2.1 is affected Version 7.0.3 is affected Version 7.2.0.1 is affected Version 7.0.4 is affected Version 7.2.1 is affected Version 7.0.5 is affected Version 7.3.0 is affected Version 7.2.2 is affected Version 7.2.3 is affected Version 7.3.1 is affected Version 7.2.4 is affected Version 7.0.6 is affected Version 7.2.5 is affected Version 7.2.4.1 is affected Version 7.3.1.1 is affected Version 7.4.0 is affected Version 7.0.6.1 is affected Version 7.2.5.1 is affected Version 7.4.1 is affected Version 7.2.6 is affected Version 7.0.6.2 is affected Version 7.4.1.1 is affected Version 7.2.7 is affected Version 7.2.5.2 is affected Version 7.3.1.2 is affected Version 7.2.8 is affected Version 7.6.0 is affected Version 7.4.2 is affected Version 7.2.8.1 is affected Version 7.0.6.3 is affected Version 7.4.2.1 is affected Version 7.2.9 is affected Version 7.0.7 is affected Version 7.7.0 is affected Version 7.4.2.2 is affected Version 7.2.10 is affected Version 7.6.1 is affected Version 7.4.2.3 is affected Version 7.0.8 is affected Version 7.6.2 is affected Version 7.7.10 is affected Version 7.7.11 is affected Version 7.0.8.1 is affected Version 7.6.2.1 is affected Version 7.7.10.1 is affected Version 7.4.2.4 is affected Version 7.2.10.2 is affected Version 7.4.3 is affected Version 7.6.4 is affected Version 10.0.0 is affected Version 7.4.4 is affected Version 7.0.9 is affected Version 7.2.11 is affected Version 7.4.7 is affected Version 7.4.8 is affected Version 7.2.12 is affected Version 7.7.13 is affected Version 10.0.2 is affected

Exploits

In August 2026, the Cisco Product Security Incident Response Team (PSIRT) became aware of active exploitation of this vulnerability. Cisco strongly recommends that customers upgrade to a fixed software release to remediate this vulnerability.

References

cisco-sa-asaftd-vpn-dos-dzv4mQFF

Problem Types

Improper Clearing of Heap Memory Before Release ('Heap Inspection') cwe