🔐 CVE Alert

CVE-2026-20039

HIGH 8.6

Cisco Adaptive Security Appliance and Firepower Threat Defense Software SSL VPN Authentication Denial of Service Vulnerability

CVSS Score
8.6
EPSS Score
0.0%
EPSS Percentile
0th

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.

CWE CWE-244
Vendor cisco
Product cisco secure firewall adaptive security appliance (asa) software
Ecosystems
Industries
NetworkingTelecommunications
Published Mar 4, 2026
Last Updated Mar 5, 2026
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CVSS v3 Breakdown

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Changed
Confidentiality
None
Integrity
None
Availability
High

Affected Versions

Cisco / Cisco Secure Firewall Adaptive Security Appliance (ASA) Software
9.12.3 9.12.1 9.12.2 9.12.4 9.12.3.2 9.12.3.7 9.12.2.5 9.12.3.12 9.12.1.3 9.12.2.4 9.12.1.2 9.12.2.9 9.12.3.9 9.12.2.1 9.12.4.2 9.12.4.4 9.12.4.7 9.12.4.8 9.12.4.10 9.12.4.13 9.12.4.18 9.12.4.24 9.16.1 9.12.4.26 9.16.1.28 9.12.4.29 9.16.2 9.12.4.30 9.16.2.3 9.12.4.35 9.16.2.7 9.12.4.37 9.17.1 9.16.2.11 9.16.2.13 9.12.4.39 9.12.4.38 9.16.2.14 9.17.1.7 9.12.4.40 9.16.3.3 9.16.3 9.16.3.14 9.17.1.9 9.12.4.41 9.17.1.10 9.18.1 9.12.4.47 9.16.3.15 9.18.1.3 9.17.1.11 9.12.4.48 9.18.2 9.16.3.19 9.17.1.13 9.12.4.50 9.17.1.15 9.12.4.52 9.16.3.23 9.18.2.5 9.16.4 9.12.4.54 9.17.1.20 9.18.2.7 9.19.1 9.16.4.9 9.12.4.55 9.18.2.8 9.16.4.14 9.18.3 9.19.1.5 9.12.4.56 9.17.1.30 9.19.1.9 9.18.3.39 9.16.4.19 9.12.4.58 9.19.1.12 9.18.3.46 9.16.4.27 9.19.1.18 9.18.3.53 9.18.3.55 9.16.4.38 9.17.1.33 9.12.4.62 9.16.4.39 9.18.3.56 9.20.1 9.16.4.42 9.19.1.22 9.18.4 9.20.1.5 9.18.4.5 9.19.1.24 9.16.4.48 9.18.4.8 9.20.2 9.19.1.27 9.12.4.65 9.16.4.55 9.18.4.22 9.20.2.10 9.16.4.57 9.19.1.28 9.17.1.39 9.12.4.67 9.18.4.24 9.20.2.21 9.16.4.61 9.19.1.31 9.18.4.29 9.20.2.22 9.16.4.62 9.18.4.34 9.20.3 9.16.4.67 9.16.4.70 9.18.4.40 9.23.1 9.22.1.1 9.16.4.71 9.20.3.4 9.18.4.47 9.20.3.7 9.17.1.45 9.19.1.37 9.17.1.46 9.16.4.76 9.20.3.9 9.19.1.38 9.18.4.50 9.22.1.3 9.20.3.10 9.22.1.2 9.18.4.52 9.20.3.13 9.22.1.6 9.18.4.53 9.16.4.82 9.22.2 9.19.1.42
Cisco / Cisco Secure Firewall Threat Defense (FTD) Software
6.4.0.1 6.4.0.2 6.4.0.5 6.4.0 6.4.0.3 6.4.0.4 6.4.0.6 6.4.0.7 6.4.0.8 6.4.0.9 6.4.0.10 6.4.0.11 6.4.0.12 7.0.0 7.0.0.1 7.0.1 7.1.0 6.4.0.13 7.0.1.1 6.4.0.14 7.1.0.1 7.0.2 6.4.0.15 7.2.0 7.0.2.1 7.0.3 7.1.0.2 7.2.0.1 7.0.4 7.2.1 7.0.5 6.4.0.16 7.3.0 7.2.2 7.2.3 7.3.1 7.1.0.3 7.2.4 7.0.6 7.2.5 7.2.4.1 7.3.1.1 7.4.0 6.4.0.17 7.0.6.1 7.2.5.1 7.4.1 7.2.6 7.0.6.2 7.4.1.1 6.4.0.18 7.2.7 7.2.5.2 7.3.1.2 7.2.8 7.6.0 7.4.2 7.2.8.1 7.0.6.3 7.4.2.1 7.2.9 7.0.7 7.7.0 7.4.2.2 7.4.2.3 7.0.8 7.0.8.1 7.4.2.4

References

NVD ↗ CVE.org ↗ EPSS Data ↗
sec.cloudapps.cisco.com: https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asaftd-vpn-dos-SpOFF2Re