CVE-2026-20349

HIGH KEV

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

Title source: cna
STIX 2.1

Exploitation Summary

CVE-2026-20349 is actively exploited and listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, added August 11, 2026.

Description

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.

Scores

CVSS v3 8.6
Attack Vector NETWORK
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H

CISA SSVC

Vulnrichment
Exploitation active
Automatable yes
Technical Impact partial

Details

CISA KEV 2026-08-11
VulnCheck KEV 2026-08-11
ENISA EUVD EUVD-2026-56643
CWE
CWE-244
Status published
Products (50)
Cisco/Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.16.1
Cisco/Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.16.1.28
Cisco/Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.16.2
Cisco/Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.16.2.11
Cisco/Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.16.2.13
Cisco/Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.16.2.14
Cisco/Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.16.2.3
Cisco/Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.16.2.7
Cisco/Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.16.3
Cisco/Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.16.3.14
... and 40 more
Published Aug 11, 2026
KEV Added Aug 11, 2026
Tracked Since Aug 11, 2026