CVE-2025-31104: Fortinet FortiADC RCE Vulnerability

CVE-2025-31104 Overview

CVE-2025-31104 is an OS Command Injection vulnerability (CWE-78) affecting Fortinet FortiADC, a high-performance Application Delivery Controller used for load balancing and web application acceleration. This vulnerability allows authenticated attackers to execute unauthorized operating system commands on affected systems through specially crafted HTTP requests.

The vulnerability stems from improper neutralization of special elements used in OS commands within the FortiADC web management interface. When user-supplied input is passed to underlying system commands without adequate sanitization, attackers with valid credentials can inject malicious commands that execute with the privileges of the FortiADC application.

Critical Impact
Authenticated attackers can achieve arbitrary command execution on FortiADC appliances, potentially leading to complete system compromise, data exfiltration, lateral movement within the network, or disruption of critical load balancing services.

Affected Products

FortiADC 7.6.0 through 7.6.1
FortiADC 7.4.0 through 7.4.6
FortiADC 7.2.0 through 7.2.7
FortiADC 7.1.0 through 7.1.4
FortiADC 7.0 all versions
FortiADC 6.2 all versions
FortiADC 6.1 all versions

Discovery Timeline

2025-06-10 - CVE-2025-31104 published to NVD
2025-07-22 - Last updated in NVD database

Technical Details for CVE-2025-31104

Vulnerability Analysis

This OS Command Injection vulnerability exists within FortiADC's web management interface where user-controllable input is incorporated into operating system commands without proper sanitization. The flaw allows authenticated users to break out of the intended command context and execute arbitrary system commands.

FortiADC, as an Application Delivery Controller, typically operates with elevated privileges to manage network traffic and system configurations. When command injection occurs in this context, the injected commands inherit these elevated privileges, significantly amplifying the potential impact.

The attack requires network access and valid authentication credentials, meaning the attacker must first obtain legitimate access to the FortiADC management interface. However, once authenticated, the command injection can be triggered through crafted HTTP requests to vulnerable endpoints, bypassing normal access controls.

Root Cause

The root cause is inadequate input validation and sanitization of user-supplied data before it is passed to system shell commands. The vulnerable code paths fail to properly escape or neutralize shell metacharacters such as semicolons (;), pipes (|), backticks, and command substitution sequences ($()). This allows attackers to terminate the intended command and append malicious instructions that the operating system will execute.

Attack Vector

The attack is conducted over the network through the FortiADC web management interface. An authenticated attacker submits specially crafted HTTP requests containing OS command injection payloads within vulnerable parameters. These payloads exploit insufficient input validation to inject commands that are subsequently executed by the underlying operating system with the privileges of the FortiADC service.

The vulnerability can be exploited through various HTTP methods depending on the specific vulnerable endpoint, with malicious payloads potentially embedded in query parameters, POST body fields, or HTTP headers processed by the application.

Detection Methods for CVE-2025-31104

Indicators of Compromise

Unusual process spawning from FortiADC web service processes (e.g., sh, bash, wget, curl, nc)
Unexpected outbound network connections from FortiADC appliances to external IP addresses
Anomalous authentication activity followed by suspicious administrative actions
Unexpected file system modifications or new files in temporary directories
Evidence of data exfiltration or command-and-control communication patterns

Detection Strategies

Monitor FortiADC access logs for HTTP requests containing shell metacharacters (;, |, $(), backticks) in parameters
Implement network intrusion detection rules to identify command injection patterns in HTTP traffic to FortiADC management interfaces
Enable and review FortiADC system logs for unexpected command execution or process creation events
Deploy endpoint detection and response (EDR) capabilities to monitor for anomalous behavior on FortiADC systems

Monitoring Recommendations

Establish baseline activity for FortiADC management interface access and alert on deviations
Configure SIEM alerts for authentication events followed by unusual HTTP request patterns
Monitor for privilege escalation attempts or unexpected administrative account activity
Implement network segmentation monitoring to detect lateral movement from compromised FortiADC appliances

How to Mitigate CVE-2025-31104

Immediate Actions Required

Restrict access to the FortiADC management interface to trusted networks and IP addresses only
Review and audit all accounts with access to FortiADC, removing unnecessary privileges
Enable multi-factor authentication for FortiADC administrative access where supported
Monitor FortiADC systems for signs of exploitation while awaiting patch deployment

Patch Information

Fortinet has released security updates to address this vulnerability. Organizations should review the Fortinet Security Advisory FG-IR-25-099 for specific patching guidance and upgrade to fixed versions:

FortiADC 7.6.x: Upgrade to 7.6.2 or later
FortiADC 7.4.x: Upgrade to 7.4.7 or later
FortiADC 7.2.x: Upgrade to 7.2.8 or later
FortiADC 7.1.x: Upgrade to a fixed branch
FortiADC 7.0.x, 6.2.x, 6.1.x: Upgrade to a supported fixed branch

Consult the official Fortinet advisory for the most current version recommendations.

Workarounds

Implement strict network access controls to limit management interface access to authorized administrator workstations
Deploy a web application firewall (WAF) in front of the FortiADC management interface to filter malicious requests
Disable remote management access entirely if not required and manage FortiADC via console access
Implement network segmentation to isolate FortiADC management interfaces from general network access

bash

# Example: Restrict FortiADC management access to specific trusted hosts
# Configure trusted host restrictions in FortiADC system settings
config system admin
    edit "admin"
        set trusthost1 10.0.0.0/24
        set trusthost2 192.168.1.0/24
    next
end