High [CVE-2026-20039] Cisco Secure Firewall Adaptive Security Appliance and Secure Firewall Threat Defense Software VPN Web Server Denial of Service Vulnerability
This high-severity Cisco advisory covers CVE-2026-20039 affecting Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.12.1.2, Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.12.1.3, Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.12.2.4.
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Summary
A vulnerability in the VPN web server of Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and Cisco Secure Firewall Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. This vulnerability is due to ineffective memory management of the VPN web server.
An attacker could exploit this vulnerability by sending a large number of crafted HTTP requests to an affected device. A successful exploit could allow the attacker to cause the device to reload, resulting in a DoS condition.
Cisco has r…
Affected products named by the advisory: Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.12.1.2; Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.12.1.3; Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.12.2.4; Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.12.2.5; and 3 more.
- Scope: At the time of publication, this vulnerability affected Cisco products if they were running a vulnerable release of Cisco Secure Firewall ASA Software or Secure FTD Software with one or both of the following features configured:
Official advisory · high-confidence parse· fetched 2 months ago·verify at source
Fixed versions
No fixed release is recorded yet. That does not prove no patch exists — confirm against the vendor advisory.
Official advisory · high-confidence parse· fetched 2 months ago·verify at source
Mitigation checklist
- There are no workarounds that address this vulnerability.
Official advisory · high-confidence parse· fetched 2 months ago·verify at source
Discussion(0)
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