CVE-2026-20009
CVE-2026-20009 is a medium-severity vulnerability in Cisco Adaptive Security Appliance Software with a CVSS 3.x base score of 5.3. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-138.
Key facts
- Severity: Medium (CVSS 3.x base score 5.3)
- EPSS exploit prediction: 0% (30th percentile)
- Actively exploited: Not listed in CISA KEV
- EU (EUVD) id: EUVD-2026-9429
- Weakness: CWE-138
- Affected product: Cisco Adaptive Security Appliance Software
- Published:
- Last modified:
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.
Frequently asked questions
- What is CVE-2026-20009?
- 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.
- How severe is CVE-2026-20009?
- CVE-2026-20009 has a CVSS 3.x base score of 5.3, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is low, integrity none, and availability none.
- Is CVE-2026-20009 being actively exploited?
- It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (30th percentile), an estimate of the probability of exploitation in the next 30 days.
- What products are affected by CVE-2026-20009?
- CVE-2026-20009 affects Cisco Adaptive Security Appliance Software. See the affected-products list for the exact vulnerable versions.
- How do I fix CVE-2026-20009?
- Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
- Does CVE-2026-20009 have an EU (EUVD) identifier?
- Yes. CVE-2026-20009 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-9429.
- When was CVE-2026-20009 published?
- CVE-2026-20009 was published on 2026-03-04 and last updated on 2026-06-17.
References
Affected products (1)
- cpe:2.3:o:cisco:adaptive_security_appliance_software:*:*:*:*:*:*:*:*
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