CVE-2025-47295: Fortinet FortiOS DoS Vulnerability

CVE-2025-47295 Overview

A buffer over-read vulnerability has been identified in Fortinet FortiOS that affects the FortiGate to FortiManager (FGFM) daemon. This vulnerability allows a remote unauthenticated attacker to send specially crafted requests that may cause the FGFM daemon to crash under rare conditions outside of the attacker's control.

Critical Impact

Remote unauthenticated attackers may cause a denial of service condition by crashing the FGFM daemon, potentially disrupting FortiGate to FortiManager communication and management operations.

Affected Products

• Fortinet FortiOS versions 7.4.0 through 7.4.3
• 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-2025-47295 published to NVD
• 2025-06-04 - Last updated in NVD database

Technical Details for CVE-2025-47295

Vulnerability Analysis

This vulnerability is classified as a buffer over-read (CWE-126, CWE-125), a type of out-of-bounds read vulnerability that occurs when a program reads data beyond the boundaries of an allocated buffer. In the context of the FortiOS FGFM daemon, this flaw enables processing of malformed input that causes the daemon to read memory beyond intended boundaries.

The FGFM (FortiGate to FortiManager) daemon is responsible for communication between FortiGate appliances and FortiManager for centralized management operations. When a specially crafted request is received, the daemon fails to properly validate input boundaries, resulting in an over-read condition that can lead to a crash.

While the impact is limited to availability (denial of service) rather than confidentiality or integrity compromise, organizations relying on FortiManager for centralized management may experience disruption if the FGFM daemon crashes.

Root Cause

The root cause of this vulnerability lies in improper bounds checking within the FGFM daemon's request parsing logic. When handling incoming requests, the daemon fails to adequately validate the length of certain input fields before attempting to read them. This results in the daemon reading beyond the allocated buffer boundaries, triggering a crash condition.

The vulnerability is categorized under CWE-126 (Buffer Over-read) and CWE-125 (Out-of-bounds Read), both of which relate to memory access violations where read operations extend beyond the intended memory region.

Attack Vector

The attack vector is network-based, allowing remote unauthenticated attackers to target vulnerable FortiOS devices. However, successful exploitation requires rare conditions that are outside of the attacker's direct control, significantly reducing the practical exploitability.

To exploit this vulnerability, an attacker would need to:

1. Have network access to the FGFM daemon service on a vulnerable FortiOS device
2. Craft a malicious request designed to trigger the buffer over-read condition
3. Send the request at a time when the rare conditions necessary for exploitation are present

The vulnerability occurs in the network request handling path, but the specific rare conditions required for successful exploitation limit the attack's reliability and predictability.

Detection Methods for CVE-2025-47295

Indicators of Compromise

• Unexpected crashes or restarts of the FGFM daemon service on FortiGate devices
• Anomalous network traffic patterns targeting the FGFM communication ports
• Log entries indicating daemon crashes or memory access violations in FortiOS system logs
• Repeated connection failures between FortiGate and FortiManager

Detection Strategies

• Monitor FortiOS system logs for FGFM daemon crash events or unexpected restarts
• Implement network intrusion detection signatures for malformed FGFM protocol requests
• Configure alerting for abnormal patterns of FGFM daemon behavior or service interruptions
• Deploy packet capture and analysis on management network segments to identify suspicious traffic

Monitoring Recommendations

• Enable verbose logging on FortiOS devices to capture detailed daemon activity
• Implement real-time monitoring of FortiGate to FortiManager connectivity status
• Configure SIEM alerting rules for FGFM-related errors and service disruptions
• Regularly review FortiOS crash dumps and diagnostic information for signs of exploitation attempts

How to Mitigate CVE-2025-47295

Immediate Actions Required

• Review the Fortinet Security Advisory FG-IR-24-381 for detailed guidance
• Identify all FortiOS devices running affected versions (7.4.0-7.4.3, 7.2.0-7.2.7, 7.0.0-7.0.14)
• Plan and schedule upgrades to patched FortiOS versions as soon as possible
• Restrict network access to FGFM daemon services to trusted management networks only

Patch Information

Fortinet has addressed this vulnerability in updated FortiOS releases. Organizations should upgrade to FortiOS versions that are not affected by this vulnerability:

• For FortiOS 7.4.x: Upgrade to version 7.4.4 or later
• For FortiOS 7.2.x: Upgrade to version 7.2.8 or later
• For FortiOS 7.0.x: Upgrade to version 7.0.15 or later

Refer to the Fortinet Security Advisory FG-IR-24-381 for complete patch information and upgrade guidance.

Workarounds

• Implement network segmentation to restrict access to FGFM daemon ports from untrusted networks
• Configure firewall rules to limit FGFM communication to authorized FortiManager IP addresses only
• Monitor FGFM daemon health and configure automated recovery mechanisms for service restarts
• Consider temporarily disabling FGFM if FortiManager integration is not critical until patches can be applied

Network access restrictions can be implemented through FortiOS local-in policies to limit which source addresses can connect to management services. Consult Fortinet documentation for specific configuration guidance.