FortiSandbox OS Command Injection Vulnerability Allows Attackers to Execute Arbitrary Code

A critical security vulnerability has been disclosed in Fortinet’s FortiSandbox platform, exposing organizations to potential system compromise.

The flaw, identified as an OS Command Injection vulnerability, allows authenticated attackers to execute arbitrary commands on the underlying operating system.

Given FortiSandbox’s pivotal role in advanced threat detection and analysis of malicious files, this vulnerability poses a significant risk to network security posture if left unaddressed.

Technical Analysis and Exploitation Risks

The vulnerability is tracked as CVE-2025-53949 and carries a CVSS v3.1 severity score of 7.0 (High). It is classified under CWE-78, which covers “Improper Neutralization of Special Elements used in an OS Command.”

The security defect resides specifically within the GUI component of the FortiSandbox appliance.

The root cause of the issue is insufficient validation of user-supplied input contained in specific HTTP requests.

When an attacker sends a crafted request to the vulnerable interface, the system fails to properly sanitize the input before passing it to the operating system shell.

This failure allows the attacker to “inject” malicious commands that the server executes with the application’s privileges.

Successful exploitation allows the attacker to execute arbitrary code, modify system files, or disrupt services.

This directly impacts the confidentiality, integrity, and availability of the appliance.

Although the vulnerability requires an authenticated attacker, which mitigates the risk of widespread automated scanning, it remains a severe threat in scenarios where insider threats exist or attacker credentials have been compromised.

Fortinet has acknowledged the severity of this issue and has released patches to address the vulnerability.

The company urges all customers to upgrade their deployments immediately to prevent potential exploitation.

The advisory, released on December 9, 2025, under identifier FG-IR-25-479, specifies that users on the 5.0 and 4.4 branches must upgrade to versions 5.0.3 and 4.4.8, respectively.

Organizations running older versions, such as the 4.2 and 4.0 branches, are advised to migrate to a supported release immediately, as no direct patches are listed for those legacy lines.

In addition to applying updates, administrators should enforce strong authentication mechanisms and review system logs for any suspicious command execution originating from the web interface.

The vulnerability was reported responsibly by Jason McFadyen of Trend Research, in collaboration with the Trend Micro Zero Day Initiative.

Fortinet has also provided CVRF and CSAF packages to help enterprise security teams automate detection and remediation.

Property	Details
CVE ID	CVE-2025-53949
Vulnerability Type	OS Command Injection (CWE-78)
Severity	High (CVSS 7.0)
Affected Components	FortiSandbox GUI Component
Affected Versions	5.0.0 – 5.0.2, 4.4.0 – 4.4.7, 4.2 (All), 4.0 (All)
Fixed Versions	Upgrade to 5.0.3 or 4.4.8
Advisory ID	FG-IR-25-479
Credit	Jason McFadyen (Trend Research / ZDI)

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