CVE-2026-20009
Cisco Secure Firewall Adaptive Security Appliance SSH Partial Private Key Authentication Bypass Vulnerability
Description
A vulnerability in the implementation of the proprietary SSH stack with SSH key-based authentication in Cisco Secure Firewall Adaptive Security Appliance (ASA) Software could allow an unauthenticated, remote attacker to log in to a Cisco Secure Firewall ASA device and execute commands as a specific user. This vulnerability is due to insufficient validation of user input during the SSH authentication phase. An attacker could exploit this vulnerability by submitting crafted input during SSH authentication to an affected device. A successful exploit could allow the attacker to log in to the device as a specific user without the private SSH key of that user. To exploit this vulnerability, the attacker must possess a valid username and the associated public key. The private key is not required. Notes: Exploitation of this vulnerability does not provide the attacker with root access. The authentication, authorization, and accounting (AAA) configuration command auto-enable is not affected by this vulnerability.
Weakness: CWE-138
Affected products
| Vendor | Product | Category | Matched by |
|---|---|---|---|
| Cisco | Cisco Adaptive Security Appliance (ASA) Check your version | Firewall / NGFW | cna-assigner |
Vendor-reported products (1)
- Cisco · Cisco Secure Firewall Adaptive Security Appliance (ASA) Software
Vendor advisory
cisco-sa-asa-ssh-keybypass-cr5xPUSf
Cisco Secure Firewall Adaptive Security Appliance Software SSH Partial Private Key Authentication Bypass Vulnerability
Cisco’s rating: Medium (advisory CVSS 5.3) · Published Mar 4, 2026
Bug ID: CSCwq24081
The vendor’s rating applies to the whole advisory and can differ from this CVE’s own CVSS severity. Where this comes from