CVE-2026-20039
8.6 · HIGHOverview
CVE-2026-20039 is a high-severity vulnerability affecting cisco adaptive_security_appliance_software. It was published on March 4, 2026 and has a CVSS 3.1 base score of 8.6 (HIGH).
This vulnerability has a CVSS 3.1 base score of 8.6, rated HIGH. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.
Technical Description
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.
Remediation
Check the references section for vendor advisories and patches from cisco. Update adaptive_security_appliance_software to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
Affected Products
| Vendor | Product | Versions | Status |
|---|---|---|---|
| cisco | adaptive_security_appliance_software | >= 9.12.1, < 9.16.4.84 | Affected |
| cisco | secure_firewall_threat_defense | >= 6.4.0, < 7.0.9 | Affected |
Frequently Asked Questions
What is CVE-2026-20039?
CVE-2026-20039 is a high-severity vulnerability affecting cisco adaptive_security_appliance_software. It was published on March 4, 2026 and has a CVSS 3.1 base score of 8.6 (HIGH).
How severe is CVE-2026-20039?
This vulnerability has a CVSS 3.1 base score of 8.6, rated HIGH. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.
How do I fix or remediate CVE-2026-20039?
Check the references section for vendor advisories and patches from cisco. Update adaptive_security_appliance_software to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
How can CyberStrike help with CVE-2026-20039?
CyberStrike's AI-powered security agents can automatically detect CVE-2026-20039 across your infrastructure using autonomous pentesting, DAST scanning, and HackBrowser. The platform continuously monitors for known vulnerabilities and provides actionable remediation guidance prioritized by real-world exploitability.
How CyberStrike Helps
AI agents map your attack surface to find vulnerabilities like this one.
Automated penetration testing that runs continuously, not just quarterly.
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Browser-based exploitation validates findings with real proof-of-concept.
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