VulnerabilityPublished 4 Mar 2026

CVE-2026-20009: Cisco Secure Firewall Adaptive Security Appliance (ASA) Software · Improper Neutralization of Special Elements

Affects Cisco Secure Firewall Adaptive Security Appliance (ASA) SoftwareSource CVE Database V5

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Not known to be exploited · CVSS 5.3 Medium.

Data as of 30 Oct 2026, 06:59 UTC

CVSS 3.1 base score

5.3Medium

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.4% chance of exploitation in 30 days – higher than 34% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: Low
Integrity: None
Availability: None

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: Low: There is some loss of confidentiality. Access to some restricted information is obtained, but the attacker does not have control over what information is obtained, or the amount or kind of loss is limited. The information disclosure does not cause a direct, serious loss to the impacted component.
Integrity: None: There is no loss of integrity within the impacted component.
Availability: None: There is no impact to availability within the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 4 Mar 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 29 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Affected software

Product	Affected	Fixed in
CiscoCisco Secure Firewall Adaptive Security Appliance (ASA) Software	Affected 9.17.1 – 9.23.1.13 82 affected builds	Fixed in–

AI-suggested

Apply Cisco's security updates and patches for ASA software versions affected by CVE-2026-20009 as soon as they become available. Regularly check Cisco advisories for updates.
Restrict SSH access to Cisco ASA devices by implementing network segmentation and firewall rules that limit SSH connections to trusted management networks or IP addresses.
Enforce strong username management practices, including avoiding predictable usernames and regularly auditing authorized public keys associated with user accounts.
Enable multi-factor authentication (MFA) for device management access where supported to add an additional layer of security beyond SSH keys.
Monitor SSH login attempts and device logs for unusual authentication activity or repeated failed attempts that could indicate exploitation attempts.
Consider disabling SSH key-based authentication temporarily if feasible and switching to alternative secure management methods until patches are applied.
Conduct regular security assessments and penetration testing focused on network perimeter devices to detect potential exploitation or misconfigurations.
Educate network administrators on this vulnerability and the importance of safeguarding SSH credentials and keys.

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.  

Impact

The primary impact of CVE-2026-20009 is unauthorized access to Cisco ASA devices via SSH without possession of the private key, assuming the attacker knows a valid username and public key. While the attacker does not gain root privileges, access as a specific user could allow execution of commands with that user's permissions, potentially leading to information disclosure or lateral movement within the network. This could undermine the confidentiality of network configurations and monitoring data. The vulnerability does not affect system integrity or availability directly, nor does it allow privilege escalation to root. However, unauthorized access to firewall devices is critical because these devices control network traffic and security policies. Attackers exploiting this vulnerability could manipulate firewall rules, disable protections, or gather intelligence for further attacks. Organizations relying on Cisco ASA for perimeter defense or VPN termination could face increased risk of intrusion and data exposure. The broad range of affected versions means many deployments worldwide could be vulnerable if not patched. The lack of requirement for the private key lowers the barrier for exploitation, increasing risk if usernames and public keys are exposed or guessable.

References

sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asa-ssh-keybypass-cr5xPUSf (opens in a new tab)

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 11 Mar 2026, 19:45 UTC

Technical details

References

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