CVE-2026-25089: Fortinet FortiSandbox RCE Vulnerability

CVE-2026-25089 Overview

CVE-2026-25089 is an OS command injection vulnerability [CWE-78] affecting multiple versions of Fortinet FortiSandbox. The flaw resides in the handling of HTTP requests and allows an unauthenticated remote attacker to execute unauthorized operating system commands on the appliance. Affected releases include FortiSandbox 5.0.0 through 5.0.5, FortiSandbox 4.4.0 through 4.4.8, all FortiSandbox 4.2 versions, FortiSandbox Cloud 5.0.4 through 5.0.5, and FortiSandbox PaaS 5.0.4 through 5.0.5. Fortinet documented the issue in advisory FG-IR-26-141.

Critical Impact
An unauthenticated attacker can execute arbitrary OS commands on FortiSandbox appliances over the network using specially crafted HTTP requests, leading to full compromise of the sandboxing infrastructure.

Affected Products

Fortinet FortiSandbox 5.0.0 through 5.0.5 and 4.4.0 through 4.4.8
Fortinet FortiSandbox 4.2 (all versions)
Fortinet FortiSandbox Cloud and FortiSandbox PaaS 5.0.4 through 5.0.5

Discovery Timeline

2026-06-09 - CVE CVE-2026-25089 published to NVD
2026-06-09 - Last updated in NVD database

Technical Details for CVE-2026-25089

Vulnerability Analysis

The vulnerability is classified under [CWE-78], improper neutralization of special elements used in an OS command. FortiSandbox processes attacker-controlled input from HTTP requests and passes that input into a shell or command execution context without adequate sanitization. Because the affected endpoint does not require authentication, any network-reachable attacker can send a crafted request and reach the vulnerable code path.

Successful exploitation grants the attacker the privileges of the process handling the request, which on appliance platforms typically runs with elevated rights. This compromises the confidentiality, integrity, and availability of the sandbox, including the malware samples and analysis results it processes. The EPSS data places exploitation probability in the upper percentile range, indicating elevated interest relative to typical CVEs.

Root Cause

The root cause is a missing or insufficient input neutralization routine on an HTTP-facing handler within FortiSandbox. User-supplied parameters are concatenated into a command string that is passed to an OS-level execution function. Shell metacharacters such as ;, |, &, and backticks are not stripped or escaped before execution.

Attack Vector

The attack vector is network-based and requires no authentication or user interaction. An attacker sends a crafted HTTP request to an exposed FortiSandbox management or service interface. Embedded shell metacharacters cause the underlying shell to interpret and execute attacker-supplied commands. No verified public proof-of-concept code is available at the time of writing. Refer to the Fortinet Security Advisory FG-IR-26-141 for vendor-supplied technical detail.

Detection Methods for CVE-2026-25089

Indicators of Compromise

Unexpected outbound network connections originating from FortiSandbox management interfaces.
Presence of shell metacharacters (;, |, &&, backticks, $()) in HTTP request parameters captured in web or proxy logs targeting FortiSandbox endpoints.
Unscheduled processes, cron entries, or modified system binaries on the FortiSandbox appliance.

Detection Strategies

Inspect HTTP request logs to FortiSandbox for anomalous URI parameters or POST bodies containing shell syntax.
Correlate FortiSandbox process execution events with inbound HTTP traffic to identify command spawning tied to web requests.
Apply intrusion detection signatures that match command injection patterns directed at FortiSandbox service ports.

Monitoring Recommendations

Forward FortiSandbox system, audit, and HTTP access logs to a centralized SIEM for retention and correlation.
Alert on new child processes spawned by the FortiSandbox web service account, especially shells, wget, curl, or nc.
Monitor egress traffic from sandbox appliances for connections to non-Fortinet update destinations.

How to Mitigate CVE-2026-25089

Immediate Actions Required

Restrict network access to FortiSandbox management and service interfaces to trusted administrative networks only.
Apply the fixed versions identified in Fortinet advisory FG-IR-26-141 as soon as they are validated in your environment.
Audit FortiSandbox appliances for signs of prior compromise, including unexpected accounts, scheduled tasks, and outbound connections.

Patch Information

Fortinet provides fixed builds and upgrade guidance in advisory FG-IR-26-141. Administrators running FortiSandbox 5.0.0–5.0.5, 4.4.0–4.4.8, or any 4.2 release should upgrade to the vendor-recommended fixed versions. FortiSandbox Cloud and PaaS customers on 5.0.4–5.0.5 should coordinate with Fortinet for hosted remediation.

Workarounds

Place FortiSandbox behind a management VPN or jump host so its HTTP interfaces are not reachable from untrusted networks.
Use upstream web application firewall rules to block requests containing shell metacharacters destined for FortiSandbox URIs until patches are applied.
Disable any exposed FortiSandbox service interfaces that are not required for operational workflows.

bash

# Configuration example: restrict management access with trusted hosts
config system admin
    edit "admin"
        set trusthost1 10.0.0.0 255.255.255.0
    next
end