CVE-2025-67685: Fortinet FortiSandbox SSRF Vulnerability

CVE-2025-67685 Overview

A Server-Side Request Forgery (SSRF) vulnerability (CWE-918) has been identified in Fortinet FortiSandbox, a malware analysis and sandboxing solution. This vulnerability allows an authenticated attacker with high privileges to proxy internal requests to plaintext endpoints through crafted HTTP requests. While the attack requires authentication and elevated privileges, it could enable attackers to access internal network resources that should not be directly accessible from the FortiSandbox interface.

Critical Impact

Authenticated attackers can leverage this SSRF vulnerability to probe internal network infrastructure, potentially exposing sensitive plaintext services and facilitating further reconnaissance within the network.

Affected Products

• Fortinet FortiSandbox 5.0.0 through 5.0.4
• Fortinet FortiSandbox 4.4 all versions
• Fortinet FortiSandbox 4.2 all versions
• Fortinet FortiSandbox 4.0 all versions

Discovery Timeline

• 2026-01-13 - CVE-2025-67685 published to NVD
• 2026-01-13 - Last updated in NVD database

Technical Details for CVE-2025-67685

Vulnerability Analysis

This SSRF vulnerability allows authenticated attackers to abuse the FortiSandbox server as a proxy to make requests to internal network resources. The vulnerability is constrained to plaintext endpoints only, meaning encrypted services (HTTPS, TLS) cannot be targeted through this flaw. However, many internal services such as metadata endpoints, management interfaces, and legacy systems may still operate over plaintext HTTP or other unencrypted protocols.

The attack requires the attacker to have valid authentication credentials with high-privilege access to the FortiSandbox management interface. Once authenticated, the attacker can craft malicious HTTP requests that cause the FortiSandbox server to initiate connections to arbitrary internal hosts and ports, effectively bypassing network segmentation controls.

Root Cause

The vulnerability stems from insufficient validation of user-supplied URLs or request parameters within the FortiSandbox application. When processing certain HTTP requests, the application fails to properly restrict or validate destination addresses, allowing authenticated users to specify internal network targets. The lack of proper URL scheme validation and internal IP address filtering enables the server to be weaponized as an internal network proxy.

Attack Vector

The attack is executed over the network by an authenticated attacker with high privileges. The attacker crafts specially formatted HTTP requests through the FortiSandbox web interface or API that include internal network addresses as destination parameters. The FortiSandbox server processes these requests and initiates connections to the specified internal resources on behalf of the attacker.

Potential targets include:

• Internal web servers and APIs operating on plaintext HTTP
• Cloud metadata services (e.g., http://169.254.169.254/)
• Internal monitoring and management interfaces
• Database services with HTTP interfaces
• Legacy systems without TLS encryption

The vulnerability mechanism involves the FortiSandbox processing user-controlled input that specifies destination URLs or hostnames. Due to insufficient validation, internal addresses are not properly blocked, and the server initiates outbound connections to these targets. For detailed technical information, refer to the Fortinet Security Advisory FG-IR-25-783.

Detection Methods for CVE-2025-67685

Indicators of Compromise

• Unusual outbound connections from the FortiSandbox server to internal network segments
• HTTP requests from FortiSandbox to cloud metadata endpoints (e.g., 169.254.169.254)
• Authenticated sessions making repetitive requests with varying internal IP addresses or hostnames
• Access logs showing requests to internal services that typically should not receive traffic from FortiSandbox

Detection Strategies

• Monitor FortiSandbox access logs for suspicious HTTP requests containing internal IP addresses or RFC1918 ranges
• Implement network monitoring to detect unexpected outbound connections from FortiSandbox to internal services
• Review authentication logs for unusual high-privilege account activity or access patterns
• Deploy intrusion detection signatures to identify SSRF payload patterns in HTTP traffic

Monitoring Recommendations

• Enable detailed logging on FortiSandbox and forward logs to a SIEM for centralized analysis
• Configure alerts for any FortiSandbox-initiated connections to internal network ranges
• Monitor for access to sensitive internal endpoints from unexpected sources
• Implement network segmentation monitoring to detect policy violations

How to Mitigate CVE-2025-67685

Immediate Actions Required

• Review and audit all high-privilege accounts on FortiSandbox deployments for legitimacy
• Implement network-level restrictions to limit FortiSandbox outbound connectivity to only required external resources
• Apply the latest security patches from Fortinet as soon as they become available
• Consider temporary network isolation of vulnerable FortiSandbox instances until patched

Patch Information

Fortinet has addressed this vulnerability in a security advisory. Organizations should consult the Fortinet Security Advisory FG-IR-25-783 for specific patch versions and upgrade instructions. Upgrade to the latest supported FortiSandbox version that addresses this vulnerability.

Workarounds

• Restrict network access to the FortiSandbox management interface to trusted administrative networks only
• Implement egress filtering to block FortiSandbox from initiating connections to internal network ranges
• Review and minimize the number of accounts with high-privilege access to FortiSandbox
• Deploy a web application firewall (WAF) in front of FortiSandbox to detect and block SSRF payloads

# Example: Restrict FortiSandbox outbound connectivity using firewall rules
# Block access to internal RFC1918 ranges from FortiSandbox server
iptables -A OUTPUT -s <fortisandbox_ip> -d 10.0.0.0/8 -j DROP
iptables -A OUTPUT -s <fortisandbox_ip> -d 172.16.0.0/12 -j DROP
iptables -A OUTPUT -s <fortisandbox_ip> -d 192.168.0.0/16 -j DROP
# Block access to cloud metadata endpoints
iptables -A OUTPUT -s <fortisandbox_ip> -d 169.254.169.254 -j DROP