CVE-2026-20009

Cisco Secure Firewall Adaptive Security Appliance SSH Partial Private Key Authentication Bypass Vulnerability

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Published Mar 4, 2026 CVSS 3.1 · 5.3 Medium EPSS < 1% KEV · Not listed
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.&nbsp;&nbsp;

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

No advisories available
History
Type Values Removed Values Added
CPEs cpe:2.3:o:cisco:adaptive_security_appliance_software:*:*:*:*:*:*:*:*
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}
Type Values Removed Values Added
First Time appeared Cisco
Cisco adaptive Security Appliance Software
Vendors & Products Cisco
Cisco adaptive Security Appliance Software
Type Values Removed Values Added
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.&nbsp;&nbsp;
Title Cisco Secure Firewall Adaptive Security Appliance SSH Partial Private Key Authentication Bypass Vulnerability
Weaknesses CWE-138
References
Metrics cvssV3_1

{'score': 5.3, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N'}
Weaknesses

Sources

Status
PUBLISHED
Assigner
cisco
Published
Updated
Mar 5, 2026, 3:49 PM
Reserved
Oct 8, 2025, 11:59 AM

View source JSON

Updated
Mar 5, 2026, 3:49 PM

JSON

Status
Analyzed
Published
Mar 4, 2026, 6:16 PM
Modified
Jun 17, 2026, 10:16 AM

View source JSON

No data.

Updated
Apr 16, 2026, 1:30 PM

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