CVE-2026-20009
Cisco Secure Firewall Adaptive Security Appliance SSH Partial Private Key Authentication Bypass Vulnerability
- Published
- Updated
- Reserved
- Assigned by
- cisco
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.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| ciscoCNA (assigner) | 3.1 | Medium5.3 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N |
| NVDNVD · Analyzed | 3.1 | Medium5.3 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N |
- EPSS (exploitation in 30 days)
- 0.44% · top 61% of all CVEs (6 Nov 2026)
- CISA SSVC
- Exploitation: none · Automatable: yes · Technical impact: partial
The list uses the assigner's score when there is one, then CISA's, then NVD's: Medium 5.3.
Weakness
Affected products
Cisco · Cisco Secure Firewall Adaptive Security Appliance (ASA) Software
- affected 9.17.1
- affected 9.17.1.7
- affected 9.17.1.9
- affected 9.17.1.10
- affected 9.18.1
- affected 9.18.1.3
- affected 9.17.1.11
- affected 9.18.2
- affected 9.17.1.13
- affected 9.17.1.15
- affected 9.18.2.5
- affected 9.17.1.20
- affected 9.18.2.7
- affected 9.19.1
- affected 9.18.2.8
- affected 9.18.3
- affected 9.19.1.5
- affected 9.17.1.30
- affected 9.19.1.9
- affected 9.18.3.39
- affected 9.19.1.12
- affected 9.18.3.46
- affected 9.19.1.18
- affected 9.18.3.53
- affected 9.18.3.55
- affected 9.17.1.33
- affected 9.18.3.56
- affected 9.20.1
- affected 9.19.1.22
- affected 9.18.4
- affected 9.20.1.5
- affected 9.18.4.5
- affected 9.19.1.24
- affected 9.18.4.8
- affected 9.20.2
- affected 9.19.1.27
- affected 9.18.4.22
- affected 9.20.2.10
- affected 9.19.1.28
- affected 9.17.1.39
- and 42 more
What to do
Exploitation: The Cisco Product Security Incident Response Team (PSIRT) is not aware of any public announcements or malicious use of the vulnerability that is described in this advisory.
References (1)
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://trackcve.app/cve/CVE-2026-20009)Record last updated .