cisco-sa-asa-ssh-keybypass-cr5xPUSfMediumCVSS 5.3

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

Published
March 4, 2026
Last Modified
March 4, 2026

🔗 CVE IDs covered (1)

CVE-2026-20009 →

📋 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.

Cisco has released software updates that address this vulnerability. There are no workarounds that address this vulnerability.

This advisory is part of the March 2026 release of the Cisco Secure Firewall ASA, Secure FMC, and Secure FTD Software Security Advisory Bundled Publication. For a complete list of the advisories and links to them, see Cisco Event Response: March 2026 Semiannual Cisco Secure Firewall ASA, Secure FMC, and Secure FTD Software Security Advisory Bundled Publication ["https://sec.cloudapps.cisco.com/security/center/viewErp.x?alertId=ERP-75736"].

CVE-2026-20009 — Cisco Secure Firewall Adaptive Security Appliance SSH Partial Private Key Authentication Bypass Vulnerability (CVSS 3.1 5.3, CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N)

🎯 Affected products92

  • Cisco 3000 Series Industrial Security Appliances (ISA)
  • Cisco Adaptive Security Virtual Appliance (ASAv)
  • Cisco Firepower 1000 Series
  • Cisco Firepower 2100 Series
  • Cisco Firepower 4100 Series
  • Cisco Firepower 9000 Series
  • Cisco Secure Firewall 1200 Series
  • Cisco Secure Firewall 3100 Series
  • Cisco Secure Firewall 4200 Series
  • Cisco Secure Firewall Adaptive Security Appliance (ASA) Software
  • Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.17.1
  • Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.17.1.10
  • Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.17.1.11
  • Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.17.1.13
  • Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.17.1.15
  • Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.17.1.20
  • Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.17.1.30
  • Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.17.1.33
  • Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.17.1.39
  • Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.17.1.45
  • Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.17.1.46
  • 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 9.18.1
  • Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.18.1.3
  • Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.18.2
  • Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.18.2.5
  • Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.18.2.7
  • Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.18.2.8
  • Cisco Secure Firewall Adaptive Security Appliance (ASA) Software 9.18.3
  • +62 more not shown

✅ Remediation

Cisco has released software updates that address this vulnerability. https://software.cisco.com Workarounds: There are no workarounds that address this vulnerability.

🔗 References (6)