Fortinet FortiSandbox OS Command Injection Vulnerability (CVE-2026-25089) Security Advisory

1. Apply Official Security Patches

Refer to Fortinet's official advisory (FG-IR-26-141) and upgrade to the patched versions immediately:

• FortiSandbox 5.0.x users: Upgrade to 5.0.6 or higher
• FortiSandbox 4.4.x users: Upgrade to 4.4.9 or higher

2. Temporary Mitigations

If immediate patching is not feasible, implement the following workarounds:

• Restrict Management Access: Ensure that the FortiSandbox web administration GUI port (typically TCP 443) is not exposed to the public internet.
• Implement Access Control Lists (ACLs): Restrict access to the management interface to trusted internal IP addresses or dedicated VPN gateways only.
• Deploy WAF Rules: Configure Web Application Firewall (WAF) rules to detect and block suspicious HTTP requests containing OS command execution characters such as ;, &, or |.

This vulnerability (CVE-2026-25089) is an OS Command Injection (CWE-78) vulnerability residing in the web management interface of Fortinet FortiSandbox.

An unauthenticated attacker can exploit this flaw by sending specially crafted HTTP requests to the target system. Due to improper neutralization of special elements within the input validation mechanism, the malicious payload is directly concatenated and executed as an OS command.

With a CVSS score of 9.8 (Critical), this vulnerability requires low attack complexity and no user interaction, leading to full system compromise. It has been added to the CISA KEV (Known Exploited Vulnerabilities) catalog, indicating active exploitation in the wild.