CVE-2025-53679: Fortinet FortiSandbox RCE Vulnerability

CVE-2025-53679 Overview

CVE-2025-53679 is an OS command injection vulnerability [CWE-78] affecting multiple versions of Fortinet FortiSandbox and FortiSandbox Cloud. The flaw stems from improper neutralization of special elements passed to operating system commands. A remote authenticated attacker with high privileges can submit crafted HTTP or HTTPS requests to execute unauthorized code or commands on the underlying system. Fortinet documented the issue in advisory FG-IR-25-454. Successful exploitation impacts confidentiality, integrity, and availability of the appliance.

Critical Impact

Authenticated remote attackers can execute arbitrary OS commands on FortiSandbox appliances, compromising the malware analysis platform that enterprises rely on for threat detection.

Affected Products

• Fortinet FortiSandbox 5.0.0 through 5.0.2, 4.4.0 through 4.4.7, 4.2 all versions, and 4.0 all versions
• Fortinet FortiSandbox Cloud 24.1
• Fortinet FortiSandbox Cloud 23 all versions

Discovery Timeline

• 2025-12-09 - CVE-2025-53679 published to NVD
• 2026-06-01 - Last updated in NVD database

Technical Details for CVE-2025-53679

Vulnerability Analysis

The vulnerability is classified under [CWE-78], OS Command Injection. FortiSandbox accepts user-supplied input through HTTP and HTTPS request handlers and passes that input into shell command construction without adequate sanitization. An attacker who already holds privileged credentials on the appliance can embed shell metacharacters or command separators in request parameters. Those characters break out of the intended argument context and execute additional commands under the privileges of the web service.

The EPSS model places the probability of exploitation at 0.707% with a percentile of 72.494, indicating moderate predicted attacker interest relative to other published CVEs. No public proof-of-concept exploit is available at the time of writing, and CISA has not added the CVE to its Known Exploited Vulnerabilities catalog.

Root Cause

FortiSandbox builds operating system commands using request-derived strings without enforcing strict allowlists or argument escaping. When metacharacters such as ;, |, &, or backticks reach the shell, the parser treats them as control operators rather than literal data. The result is unintended command execution within the appliance's command interpreter.

Attack Vector

Exploitation requires network reachability to the FortiSandbox management interface and valid high-privilege credentials. The attacker sends a crafted HTTP or HTTPS request containing injected shell syntax in a vulnerable parameter. The appliance processes the request server-side and the injected commands run with the service account's privileges. User interaction is not required.

No verified exploit code is publicly available. Refer to the Fortinet Security Advisory FG-IR-25-454 for vendor technical details.

Detection Methods for CVE-2025-53679

Indicators of Compromise

• Unexpected child processes spawned by FortiSandbox web service accounts, particularly shell interpreters invoking system utilities.
• HTTP or HTTPS request logs containing shell metacharacters such as ;, |, &&, backticks, or $( in parameter values directed at administrative endpoints.
• Outbound network connections from the FortiSandbox appliance to unfamiliar external hosts following administrative API activity.
• New or modified files in system directories, scheduled tasks, or unexpected SSH key entries on the appliance.

Detection Strategies

• Inspect FortiSandbox audit logs for administrative API calls originating from unusual source addresses or service accounts.
• Correlate authentication events for privileged accounts with subsequent HTTP/HTTPS POST requests carrying suspicious payloads.
• Apply WAF or IDS signatures that flag shell metacharacters in JSON or form parameters sent to FortiSandbox management endpoints.

Monitoring Recommendations

• Forward FortiSandbox syslog and HTTP access logs to a centralized SIEM for retention and correlation.
• Baseline normal administrative activity and alert on deviations such as off-hours configuration changes or scripted request patterns.
• Monitor egress traffic from the appliance management interface for connections that do not match documented update or telemetry destinations.

How to Mitigate CVE-2025-53679

Immediate Actions Required

• Upgrade FortiSandbox to a fixed release as specified in Fortinet Security Advisory FG-IR-25-454.
• Restrict management interface access to dedicated administrative networks or jump hosts using firewall ACLs.
• Rotate credentials for all high-privilege FortiSandbox accounts and audit recent administrative activity.
• Enforce multi-factor authentication for administrative logins where supported.

Patch Information

Fortinet has released fixed firmware versions for affected FortiSandbox and FortiSandbox Cloud branches. Consult Fortinet Security Advisory FG-IR-25-454 for the specific target versions that remediate CVE-2025-53679 and follow the vendor upgrade path for each branch (5.0.x, 4.4.x, 4.2.x, 4.0.x, and Cloud 24.1).

Workarounds

• Limit network exposure of the FortiSandbox management interface to trusted administrators only until patches can be applied.
• Disable or restrict accounts with administrative privileges that are not strictly required for operations.
• Place a reverse proxy or WAF in front of the management interface to filter requests containing shell metacharacters in unexpected fields.