CVE-2026-20063 is a command injection vulnerability found in the command-line interface (CLI) of Cisco Secure Firewall Threat Defense (FTD) Software. The root cause is insufficient neutralization of argument delimiters in user-supplied command arguments, which allows an attacker with valid administrative credentials and local access to inject arbitrary commands. When an attacker submits specially crafted input to a vulnerable CLI command, the input is improperly parsed, enabling execution of arbitrary commands on the underlying operating system with root privileges. This vulnerability affects multiple versions of Cisco Secure FTD, including 7.6.0, 7.6.1, 7.6.2, 7.6.2.1, 7.7.0, 7.7.10, and 7.7.10.1. The attack vector requires local access and high privileges, meaning the attacker must already have administrative rights on the device. No user interaction is required beyond the attacker executing commands via the CLI. The vulnerability does not currently have known exploits in the wild but poses a significant risk due to the potential for full system compromise. The CVSS v3.1 base score is 6.0, reflecting medium severity with high impact on confidentiality and integrity but limited by the requirement for local, privileged access. Cisco has not yet published patches or mitigation details at the time of this report.

The primary impact of CVE-2026-20063 is the potential for an attacker with administrative CLI access to execute arbitrary commands as root on Cisco Secure FTD devices. This could lead to full system compromise, including unauthorized access to sensitive firewall configurations, interception or manipulation of network traffic, disruption of firewall operations, and potential pivoting to other internal systems. Confidentiality and integrity are highly impacted since the attacker can alter firewall rules or extract sensitive data. Availability impact is limited as the vulnerability does not inherently allow denial of service, but malicious commands could be crafted to disrupt service. Organizations relying on Cisco Secure FTD for perimeter security or internal segmentation could face significant risk if this vulnerability is exploited, especially in environments where administrative access controls are lax or insider threats exist. The requirement for local, privileged access limits the scope but does not eliminate risk in large or distributed networks where multiple administrators or contractors have CLI access.

To mitigate CVE-2026-20063, organizations should immediately restrict administrative CLI access to trusted personnel and enforce strong authentication and authorization controls. Network segmentation and access controls should limit local access to Cisco Secure FTD devices. Monitoring and logging of CLI commands can help detect suspicious activity. Until Cisco releases patches, administrators should avoid executing untrusted commands or scripts on affected devices. Implementing multi-factor authentication for administrative access can reduce risk of credential compromise. Regularly auditing user accounts and privileges on FTD devices will help minimize the number of users with high-level access. Once available, promptly apply Cisco’s security updates addressing this vulnerability. Additionally, consider deploying host-based intrusion detection systems on management stations to detect anomalous command injection attempts. Document and rehearse incident response procedures for potential device compromise scenarios.