Secure Firewall ASA and FTD
CVE-2026-20349: Cisco Secure Firewall Adaptive Security Appliance and Secure Firewall Threat Defense Software Remote Access SSL VPN Denial of Service Vulnerability
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.
Published
ExploitedYes, in CISA KEVAdded 11 Aug 2026
Ransomware useNot reportedPer CISA
SeverityHIGHCVSS 3.1 8.6
EPSS1.0%Chance of exploitation in 30 days
Public exploitNot tracked
FixNot yet
Automatic summary from the vendor's CVE record. We haven't written a full analysis of this vulnerability yet.
Affected and fixed versions
| Product / branch | Fixed in |
|---|---|
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.16 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.16 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.16 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.16 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.16 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.16 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.16 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.16 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.16 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.16 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.16 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.18 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.16 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.18 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.18 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.16 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.16 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.18 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.16 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.18 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.19 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.16 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.18 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.16 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.18 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.19 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.16 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.19 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.18 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.16 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.19 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.18 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.16 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.19 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.18 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.18 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.16 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.16 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.18 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.20 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.16 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.19 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.18 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.20 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.18 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.19 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.16 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.18 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.20 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.19 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.16 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.18 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.20 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.16 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.19 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.18 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.20 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.16 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.19 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.18 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.20 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.16 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.18 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.20 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.16 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.16 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.18 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.23 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.22 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.16 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.20 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.18 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.20 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.19 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.16 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.20 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.19 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.18 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.22 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.20 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.22 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.18 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.20 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.22 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.18 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.16 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.22 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.20 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.19 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.18 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.16 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.23 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.20 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.22 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.23 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.20 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.22 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.23 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.20 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.22 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.18 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.20 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.23 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.16 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.22 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.18 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.24 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.18 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.23 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.20 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.22 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.18 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.20 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.23 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.16 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.22 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.18 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.22 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.24 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.20 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.24 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.20 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.22 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.16 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.18 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.23 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.20 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.24 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.23 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.24 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.20 | See the advisory |
| Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.18 | See the advisory |
| Cisco Secure Firewall Threat Defense (FTD) Software 7.0 | See the advisory |
| Cisco Secure Firewall Threat Defense (FTD) Software 7.0 | See the advisory |
| Cisco Secure Firewall Threat Defense (FTD) Software 7.0 | See the advisory |
| Cisco Secure Firewall Threat Defense (FTD) Software 7.0 | See the advisory |
| Cisco Secure Firewall Threat Defense (FTD) Software 7.0 | See the advisory |
| Cisco Secure Firewall Threat Defense (FTD) Software 7.2 | See the advisory |
| Cisco Secure Firewall Threat Defense (FTD) Software 7.0 | See the advisory |
| Cisco Secure Firewall Threat Defense (FTD) Software 7.0 | See the advisory |
| Cisco Secure Firewall Threat Defense (FTD) Software 7.2 | See the advisory |
| Cisco Secure Firewall Threat Defense (FTD) Software 7.0 | See the advisory |
| Cisco Secure Firewall Threat Defense (FTD) Software 7.2 | See the advisory |
| Cisco Secure Firewall Threat Defense (FTD) Software 7.0 | See the advisory |
| Cisco Secure Firewall Threat Defense (FTD) Software 7.3 | See the advisory |
| Cisco Secure Firewall Threat Defense (FTD) Software 7.2 | See the advisory |
| Cisco Secure Firewall Threat Defense (FTD) Software 7.2 | See the advisory |
| Cisco Secure Firewall Threat Defense (FTD) Software 7.3 | See the advisory |
| Cisco Secure Firewall Threat Defense (FTD) Software 7.2 | See the advisory |
| Cisco Secure Firewall Threat Defense (FTD) Software 7.0 | See the advisory |
| Cisco Secure Firewall Threat Defense (FTD) Software 7.2 | See the advisory |
| Cisco Secure Firewall Threat Defense (FTD) Software 7.2 | See the advisory |
| Cisco Secure Firewall Threat Defense (FTD) Software 7.3 | See the advisory |
| Cisco Secure Firewall Threat Defense (FTD) Software 7.4 | See the advisory |
| Cisco Secure Firewall Threat Defense (FTD) Software 7.0 | See the advisory |
| Cisco Secure Firewall Threat Defense (FTD) Software 7.2 | See the advisory |
| Cisco Secure Firewall Threat Defense (FTD) Software 7.4 | See the advisory |
| Cisco Secure Firewall Threat Defense (FTD) Software 7.2 | See the advisory |
| Cisco Secure Firewall Threat Defense (FTD) Software 7.0 | See the advisory |
| Cisco Secure Firewall Threat Defense (FTD) Software 7.4 | See the advisory |
| Cisco Secure Firewall Threat Defense (FTD) Software 7.2 | See the advisory |
| Cisco Secure Firewall Threat Defense (FTD) Software 7.2 | See the advisory |
| Cisco Secure Firewall Threat Defense (FTD) Software 7.3 | See the advisory |
| Cisco Secure Firewall Threat Defense (FTD) Software 7.2 | See the advisory |
| Cisco Secure Firewall Threat Defense (FTD) Software 7.6 | See the advisory |
| Cisco Secure Firewall Threat Defense (FTD) Software 7.4 | See the advisory |
| Cisco Secure Firewall Threat Defense (FTD) Software 7.2 | See the advisory |
| Cisco Secure Firewall Threat Defense (FTD) Software 7.0 | See the advisory |
| Cisco Secure Firewall Threat Defense (FTD) Software 7.4 | See the advisory |
| Cisco Secure Firewall Threat Defense (FTD) Software 7.2 | See the advisory |
| Cisco Secure Firewall Threat Defense (FTD) Software 7.0 | See the advisory |
| Cisco Secure Firewall Threat Defense (FTD) Software 7.7 | See the advisory |
| Cisco Secure Firewall Threat Defense (FTD) Software 7.4 | See the advisory |
| Cisco Secure Firewall Threat Defense (FTD) Software 7.2 | See the advisory |
| Cisco Secure Firewall Threat Defense (FTD) Software 7.6 | See the advisory |
| Cisco Secure Firewall Threat Defense (FTD) Software 7.4 | See the advisory |
| Cisco Secure Firewall Threat Defense (FTD) Software 7.0 | See the advisory |
| Cisco Secure Firewall Threat Defense (FTD) Software 7.6 | See the advisory |
| Cisco Secure Firewall Threat Defense (FTD) Software 7.7 | See the advisory |
| Cisco Secure Firewall Threat Defense (FTD) Software 7.7 | See the advisory |
| Cisco Secure Firewall Threat Defense (FTD) Software 7.0 | See the advisory |
| Cisco Secure Firewall Threat Defense (FTD) Software 7.6 | See the advisory |
| Cisco Secure Firewall Threat Defense (FTD) Software 7.7 | See the advisory |
| Cisco Secure Firewall Threat Defense (FTD) Software 7.4 | See the advisory |
| Cisco Secure Firewall Threat Defense (FTD) Software 7.2 | See the advisory |
| Cisco Secure Firewall Threat Defense (FTD) Software 7.4 | See the advisory |
| Cisco Secure Firewall Threat Defense (FTD) Software 7.6 | See the advisory |
| Cisco Secure Firewall Threat Defense (FTD) Software 10.0 | See the advisory |
| Cisco Secure Firewall Threat Defense (FTD) Software 7.4 | See the advisory |
| Cisco Secure Firewall Threat Defense (FTD) Software 7.0 | See the advisory |
| Cisco Secure Firewall Threat Defense (FTD) Software 7.2 | See the advisory |
| Cisco Secure Firewall Threat Defense (FTD) Software 7.4 | See the advisory |
| Cisco Secure Firewall Threat Defense (FTD) Software 10.0 | See the advisory |
Always confirm against the vendor advisory, which lists every fixed hotfix.
What it is
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.
Exploitation
In August 2026, the Cisco PSIRT became aware of active exploitation of this vulnerability. Cisco strongly recommends that customers upgrade to a fixed software release to remediate this vulnerability.
CISA lists this CVE as exploited in the wild since 11 Aug 2026.
Sources
KEV status, EPSS score and vendor data refreshed automatically, last on 11 Oct 2026.