CISA Alert: CVE-2026-25108 Soliton FileZen OS Command Injection Exploited

Overview of CVE-2026-25108 and CISA’s KEV Catalog Update

The Cybersecurity and Infrastructure Security Agency (CISA) has issued an alert, adding a critical vulnerability, CVE-2026-25108, to its Known Exploited Vulnerabilities (KEV) Catalog. This action follows the confirmation of active exploitation of the vulnerability, which affects Soliton Systems K.K. FileZen OS. The vulnerability is classified as an OS Command Injection, posing significant risks to organizations utilizing the affected software. CISA’s update emphasizes the immediate need for remediation across all sectors, particularly within Federal Civilian Executive Branch (FCEB) agencies which are mandated to address KEV entries promptly. According to CISA, this type of vulnerability is a frequent attack vector for malicious cyber actors.

Technical Analysis: CVE-2026-25108

CVE-2026-25108 is an OS Command Injection vulnerability found in Soliton Systems FileZen OS. An OS Command Injection flaw allows an attacker to execute arbitrary operating system commands on the host server running the application. This typically occurs when an application constructs a system command using user-supplied input without adequate sanitization or validation. If successfully exploited, this vulnerability could grant an attacker high-privilege access, leading to complete system compromise, data exfiltration, installation of malicious software, or disruption of services. For an appliance like Soliton Systems FileZen OS, which is often used for secure file transfers and management, a compromise could have far-reaching implications, allowing attackers to access sensitive data, pivot to other internal systems, or maintain persistence within the network. The confirmed active exploitation significantly elevates the threat posture of this vulnerability from a theoretical risk to an immediate and present danger.

The Role of CISA’s Known Exploited Vulnerabilities (KEV) Catalog

CISA’s KEV Catalog is a crucial component of the United States federal government’s cybersecurity strategy, established under Binding Operational Directive (BOD) 22-01: Reducing the Significant Risk of Known Exploited Vulnerabilities. This directive mandates that FCEB agencies remediate all vulnerabilities listed in the KEV Catalog by specified due dates to protect federal networks against active threats. The catalog serves as a dynamic, living list of CVEs that are known to be actively exploited in the wild, thus representing the most pressing and immediate risks to the cyber landscape. By including CVE-2026-25108, CISA underscores its critical nature and the observed real-world impact. While BOD 22-01 specifically applies to federal agencies, CISA consistently advises all public and private sector organizations to integrate the KEV Catalog into their vulnerability management practices. Prioritizing the remediation of these identified vulnerabilities is a fundamental step in reducing exposure to cyberattacks and strengthening overall cyber resilience.

Actionable Recommendations and Mitigations

Organizations leveraging Soliton Systems K.K. FileZen OS should consider CVE-2026-25108 an urgent remediation priority due to its confirmed active exploitation and potential for severe impact. The following recommendations are critical for mitigating the risk:

• Immediate Patching: Apply all available security updates and patches from Soliton Systems K.K. for FileZen OS as soon as possible. Verify that the patches are successfully installed and the systems are no longer vulnerable.
• Vulnerability Management: Regularly consult CISA’s KEV Catalog and prioritize remediation efforts for all listed vulnerabilities as part of an ongoing, robust vulnerability management program.
• Network Segmentation: Isolate critical systems, such as file transfer appliances, from less secure network segments. This can limit an attacker’s ability to move laterally within the network if a compromise occurs.
• Least Privilege: Implement the principle of least privilege for all user accounts and services interacting with FileZen OS, reducing the potential impact of a successful command injection.
• Security Monitoring: Enhance logging and monitoring for Soliton Systems FileZen OS instances. Look for unusual process execution, unexpected outbound connections, or suspicious user activity that could indicate compromise. Deploy Endpoint Detection and Response (EDR) solutions to detect and respond to malicious activity.
• Incident Response Plan: Ensure an up-to-date incident response plan is in place and regularly tested, specifically addressing procedures for responding to an OS command injection and subsequent system compromise.