CVE-2025-47294: Fortinet FortiOS DoS Vulnerability

CVE-2025-47294 Overview

CVE-2025-47294 is an integer overflow or wraparound vulnerability affecting Fortinet FortiOS, the operating system that powers Fortinet's security appliances including firewalls and VPN solutions. This vulnerability allows a remote unauthenticated attacker to crash the csfd daemon by sending specially crafted requests, resulting in a denial of service condition.

Critical Impact

Remote unauthenticated attackers can exploit this integer overflow vulnerability to crash the csfd daemon on FortiOS devices, potentially disrupting critical network security services and perimeter defenses.

Affected Products

• Fortinet FortiOS versions 7.2.0 through 7.2.7
• Fortinet FortiOS versions 7.0.0 through 7.0.14

Discovery Timeline

• 2025-05-28 - CVE-2025-47294 published to NVD
• 2025-06-04 - Last updated in NVD database

Technical Details for CVE-2025-47294

Vulnerability Analysis

This vulnerability is classified as CWE-190 (Integer Overflow or Wraparound). Integer overflow vulnerabilities occur when an arithmetic operation attempts to create a numeric value that exceeds the range that can be represented within the available storage space. In the context of FortiOS, this integer overflow affects the csfd (Configuration Sync Fabric Daemon) daemon, which handles configuration synchronization functions within Fortinet's Security Fabric architecture.

When an attacker sends a specially crafted request to the vulnerable daemon, the integer overflow condition is triggered, causing the csfd daemon to crash. Since this daemon is responsible for fabric synchronization operations, its failure can impact the coordination and security posture of FortiGate devices operating within a Security Fabric deployment.

The vulnerability can be exploited remotely over the network without requiring any prior authentication or user interaction, making it accessible to external threat actors.

Root Cause

The root cause is an integer overflow condition in the csfd daemon's input handling logic. When processing certain request parameters, the daemon performs arithmetic operations on user-supplied values without adequate boundary checking. When the result exceeds the maximum value that can be stored in the integer variable, the value wraps around, leading to unexpected behavior and ultimately causing the daemon to crash.

Attack Vector

The attack vector is network-based, allowing remote unauthenticated attackers to target vulnerable FortiOS devices. The attacker crafts a malicious request containing values designed to trigger the integer overflow condition in the csfd daemon.

The exploitation process involves:

1. Identifying a FortiOS device running a vulnerable version (7.0.0-7.0.14 or 7.2.0-7.2.7)
2. Sending a specially crafted request to the csfd daemon with overflow-inducing values
3. The daemon processes the request, triggering the integer overflow
4. The overflow causes the daemon to crash, resulting in denial of service

For detailed technical information, refer to the Fortinet Security Advisory FG-IR-24-388.

Detection Methods for CVE-2025-47294

Indicators of Compromise

• Unexpected crashes or restarts of the csfd daemon on FortiOS devices
• Log entries indicating csfd process termination or abnormal exit codes
• Unusual network traffic patterns targeting FortiOS management interfaces
• Repeated connection attempts from unknown sources to affected services

Detection Strategies

• Monitor FortiOS system logs for csfd daemon crash events or unexpected restarts
• Implement network intrusion detection rules to identify malformed requests targeting FortiOS services
• Configure alerts for repeated daemon failures within short time windows
• Review FortiAnalyzer or syslog aggregation for patterns indicating exploitation attempts

Monitoring Recommendations

• Enable detailed logging on FortiOS devices to capture daemon status changes
• Set up automated alerts for csfd daemon availability monitoring
• Deploy network traffic analysis tools to identify anomalous requests to FortiOS devices
• Establish baseline behavior for daemon restarts to identify deviation patterns

How to Mitigate CVE-2025-47294

Immediate Actions Required

• Upgrade FortiOS to a patched version as specified in the Fortinet security advisory
• Restrict network access to FortiOS management interfaces using firewall rules
• Implement network segmentation to limit exposure of FortiOS devices to untrusted networks
• Monitor affected devices for signs of exploitation attempts

Patch Information

Fortinet has released security updates to address this vulnerability. Organizations running affected versions should upgrade to patched releases as soon as possible. Consult the Fortinet Security Advisory FG-IR-24-388 for specific version recommendations and upgrade instructions.

Workarounds

• Limit access to FortiOS management and fabric synchronization interfaces to trusted IP addresses only
• Use access control lists (ACLs) to restrict which networks can communicate with the csfd daemon
• Consider temporarily disabling Security Fabric features if they are not operationally critical until patching is completed
• Implement rate limiting on inbound connections to affected services

# Example: Restrict management access to trusted networks only
config system interface
    edit "mgmt"
        set allowaccess ping https ssh
        set trusted-hosts 10.0.0.0/8 192.168.1.0/24
    next
end