Cisco Adaptive Security Appliance and Firepower Threat Defense Software SSL VPN Authentication Denial of Service Vulnerability
Summary
| CVE | CVE-2026-20039 |
|---|---|
| State | PUBLISHED |
| Assigner | cisco |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-03-04 18:16:17 UTC |
| Updated | 2026-04-16 20:01:23 UTC |
| 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. |
Risk And Classification
Primary CVSS: v3.1 8.6 HIGH from [email protected]
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
Problem Types: CWE-244 | CWE-244 Improper Clearing of Heap Memory Before Release ('Heap Inspection')
| Version | Source | Type | Score | Severity | Vector |
|---|---|---|---|---|---|
| 3.1 | [email protected] | Primary | 8.6 | HIGH | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H |
| 3.1 | CNA | CVSSV3_1 | 8.6 | HIGH | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H |
CVSS v3.1 Breakdown
Attack Vector
NetworkAttack Complexity
LowPrivileges Required
NoneUser Interaction
NoneScope
ChangedConfidentiality
NoneIntegrity
NoneAvailability
HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
NVD Known Affected Configurations (CPE 2.3)
| Type | Vendor | Product | Version | Update | Edition | Language |
|---|---|---|---|---|---|---|
| Operating System | Cisco | Adaptive Security Appliance Software | All | All | All | All |
Vendor Declared Affected Products
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asaftd... | [email protected] | sec.cloudapps.cisco.com | Vendor Advisory |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
No vendor comments have been submitted for this CVE.
Additional Advisory Data
Exploits
CNA: The Cisco Product Security Incident Response Team (PSIRT) is not aware of any public announcements or malicious use of the vulnerability that is described in this advisory.
There are currently no legacy QID mappings associated with this CVE.