CVE-2026-20009: cisco adaptive_security_appliance_software

Vulnerability summary

CVE-2026-20009 is a medium (CVSS 5.3) vulnerability in cisco adaptive_security_appliance_software. EPSS estimates a 0.40% chance of exploitation in the next 30 days, higher than 33.5% of scored vulnerabilities.

Timeline

1. 04-03-2026
   PublishedVulnerability first disclosed.
2. 05-03-2026
   Last modifiedVulnerability information updated.

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.

• CWE-138Improper Neutralization of Special ElementsThe product receives input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could be interpreted as control elements or syntactic markers when they are sent to a downstream component.