CVE-2026-25108: FileZen OS Command Injection Vulnerability

CVE-2026-25108 Overview

FileZen contains an OS command injection vulnerability (CWE-78) that allows authenticated users to execute arbitrary operating system commands on the underlying server. When the FileZen Antivirus Check Option is enabled, a logged-in user may send a specially crafted HTTP request to execute an arbitrary OS command, potentially leading to complete system compromise.

Critical Impact

Authenticated attackers can execute arbitrary OS commands on FileZen servers with the Antivirus Check Option enabled, potentially leading to full system compromise, data exfiltration, or lateral movement within the network.

Affected Products

• FileZen (with Antivirus Check Option enabled)
• Soliton FileZen file sharing appliances

Discovery Timeline

• 2026-02-13 - CVE-2026-25108 published to NVD
• 2026-02-13 - Last updated in NVD database

Technical Details for CVE-2026-25108

Vulnerability Analysis

This OS command injection vulnerability resides in the FileZen application's handling of HTTP requests when the Antivirus Check Option feature is enabled. The vulnerability allows authenticated users to inject malicious commands that are executed at the operating system level with the privileges of the FileZen application process.

Command injection vulnerabilities occur when an application passes unsanitized user-controllable data to a system shell or command interpreter. In this case, the FileZen application fails to properly validate or sanitize input within HTTP requests related to the antivirus checking functionality, allowing attackers to append or inject arbitrary shell commands.

The network-accessible nature of this vulnerability combined with the relatively low barrier to exploitation (only requiring authenticated access) makes this a significant risk for organizations using FileZen file sharing appliances. Successful exploitation could result in confidentiality, integrity, and availability impacts on the affected system.

Root Cause

The root cause of this vulnerability is improper input validation (CWE-78: Improper Neutralization of Special Elements used in an OS Command) within the FileZen Antivirus Check Option functionality. User-supplied input from HTTP requests is passed to operating system command execution functions without adequate sanitization of shell metacharacters or command separators, enabling command injection attacks.

Attack Vector

The attack is network-based and requires the attacker to have authenticated access to the FileZen application. The exploitation path involves:

1. Attacker authenticates to the FileZen web interface with valid credentials
2. Attacker ensures the Antivirus Check Option is enabled on the target system
3. Attacker crafts a malicious HTTP request containing shell command injection payloads
4. The application processes the request and passes unsanitized input to the OS command interpreter
5. Arbitrary commands execute with the privileges of the FileZen application process

The vulnerability can be exploited through specially crafted HTTP requests targeting the antivirus checking functionality. Common command injection techniques such as command chaining using semicolons (;), pipes (|), or backticks may be effective depending on the underlying implementation. For detailed technical information, refer to the JVN Security Advisory JVN84622767 and Soliton Support Notice 006657.

Detection Methods for CVE-2026-25108

Indicators of Compromise

• Unusual HTTP requests to FileZen containing shell metacharacters such as ;, |, $(), or backticks in request parameters
• Unexpected child processes spawned by the FileZen web application process
• Anomalous outbound network connections originating from the FileZen server
• Unauthorized file modifications or new files created in system directories
• Evidence of command execution in application or system logs

Detection Strategies

• Monitor HTTP request logs for patterns consistent with command injection attempts, including shell metacharacters and common injection payloads
• Deploy web application firewall (WAF) rules to detect and block requests containing OS command injection patterns
• Implement process monitoring on FileZen servers to detect unexpected command execution or child process spawning
• Configure SIEM rules to correlate authentication events with suspicious HTTP request patterns

Monitoring Recommendations

• Enable verbose logging for the FileZen application and forward logs to a centralized SIEM
• Monitor for unusual process trees originating from the FileZen web server process
• Track outbound network connections from FileZen servers for potential data exfiltration or command-and-control activity
• Implement file integrity monitoring on critical system directories

How to Mitigate CVE-2026-25108

Immediate Actions Required

• Apply the security patch from Soliton as described in Support Notice 006657
• Review authentication logs to identify potentially compromised accounts
• Audit FileZen servers for indicators of compromise
• Restrict network access to FileZen administrative interfaces to trusted IP ranges

Patch Information

Soliton has released security updates to address this vulnerability. Organizations should consult the Soliton Support Notice 006657 for specific patch information and upgrade instructions. Apply the latest available security patches immediately to remediate this vulnerability.

Workarounds

• Disable the Antivirus Check Option feature if not required for business operations until patches can be applied
• Implement network segmentation to limit access to FileZen servers from untrusted networks
• Deploy a web application firewall (WAF) with command injection detection rules in front of FileZen deployments
• Enforce strict access controls to minimize the number of authenticated users who could potentially exploit this vulnerability
• Monitor for exploitation attempts while implementing permanent remediation

Organizations should prioritize patching as the primary remediation strategy, as workarounds may not fully mitigate the risk of exploitation.