CVE-2026-20039
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.
Key facts
- CVSS score
- 8.6 (v3.1)
- Severity
- HIGH
- CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H- Weakness (CWE)
- CWE-244
- EPSS score
- 0.4% (29th percentile)
- In CISA KEV
- No
- In EU EUVD
- Yes (EUVD-2026-9434)
- Published
- March 4, 2026
- NVD last modified
- August 11, 2026
- Status
- Analyzed
EU Vulnerability Database (EUVD)
This vulnerability is also tracked by ENISA as EUVD-2026-9434 in the EU Vulnerability Database. Last updated in EUVD on March 5, 2026.
View on the EU Vulnerability DatabaseAffected products
- cisco / adaptive security appliance software
- cisco / secure firewall threat defense
Certified products that may be affected
2 FIPS 140 or Common Criteria certified products, from automated matching by sec-certs.org.
- Cisco Secure Firewall Threat Defense (FTD) 7.4 with Secure Firewall Management Center (FMC) 7.4 and Secure Client 5.1 - Cisco Systems, Inc. - Common Criteria NSCIB-CC-2400046-01-CR - active
- Cisco Secure Firewall Threat Defense Virtual 7.4 with FMC/FMCv - Cisco Systems, Inc. - Common Criteria CCEVS-VR-VID-11510-2025 - active
References
Last updated September 17, 2026 · Source: NVD, CISA KEV, FIRST.org EPSS
Query CVEs from your AI assistant
The CVE/NVD Explorer brain answers CVE questions directly inside Claude, ChatGPT, or any MCP assistant — always up to date, no setup. Add it once and stop pasting advisories into chat.
Add the CVE brain