Medium [CVE-2026-20009] Cisco Secure Firewall Adaptive Security Appliance Software SSH Partial Private Key Authentication Bypass Vulnerability
This medium-severity Cisco advisory covers CVE-2026-20009 affecting Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.17.1.7, Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.17.1.9, Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.17.1.10.
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Summary
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 de…
Affected products named by the advisory: Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.17.1.7; Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.17.1.9; Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.17.1.10; Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.17.1.11; and 5 more.
- Scope: At the time of publication, this vulnerability affected Cisco products if they were running a vulnerable release of Cisco Secure Firewall ASA Software and the following conditions were met:
Official advisory · high-confidence parse· fetched 2 months ago·verify at source
Fixed versions
No fixed release is recorded yet. That does not prove no patch exists — confirm against the vendor advisory.
Official advisory · high-confidence parse· fetched 2 months ago·verify at source
Mitigation checklist
- There are no workarounds that address this vulnerability.
Official advisory · high-confidence parse· fetched 2 months ago·verify at source
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