CVE-2024-26007: Fortinet FortiOS DoS Vulnerability

CVE-2024-26007 Overview

CVE-2024-26007 is a denial-of-service vulnerability in Fortinet FortiOS 7.4.1 caused by improper check or handling of exceptional conditions [CWE-703]. An unauthenticated remote attacker can send crafted HTTP requests to the administrative interface and trigger a denial-of-service condition. The vulnerability requires no authentication, no user interaction, and is exploitable over the network. Fortinet published an advisory tracking this issue as FG-IR-24-017.

Critical Impact
Unauthenticated attackers can disable the FortiOS administrative interface remotely via crafted HTTP requests, blocking administrators from managing the device during an active incident.

Affected Products

Fortinet FortiOS 7.4.1
Fortinet FortiGate appliances running the affected FortiOS version
Deployments exposing the FortiOS administrative HTTP/HTTPS interface

Discovery Timeline

2024-05-14 - CVE-2024-26007 published to NVD
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2024-26007

Vulnerability Analysis

The vulnerability resides in the FortiOS administrative HTTP interface. FortiOS 7.4.1 fails to properly check or handle exceptional conditions when parsing specific HTTP request structures. An attacker who reaches the management interface over the network can submit crafted requests that drive the service into an error state, resulting in denial of service.

The issue is classified under [CWE-703] Improper Check or Handling of Exceptional Conditions. This weakness class covers code paths that fail to anticipate malformed or unexpected input and instead crash, hang, or otherwise interrupt service availability. Confidentiality and integrity are not impacted, but availability of the management plane is fully compromised during exploitation.

Root Cause

The root cause is missing or insufficient exception handling within the FortiOS administrative web service request processing logic. Specific malformed HTTP request fields are not validated before reaching code that cannot tolerate the unexpected input. Fortinet has not publicly released the exact code path or parser component affected. Refer to the FortiGuard Security Advisory for vendor technical detail.

Attack Vector

The attack is unauthenticated and remote. An attacker requires only network reachability to the FortiOS administrative interface, typically TCP/443 or TCP/80 on the management VLAN or, in misconfigured deployments, on a WAN interface. The attacker sends one or more crafted HTTP requests targeting the management service. No credentials, tokens, or prior session establishment are required.

The vulnerability is described in prose because no verified public proof-of-concept code is available. See the FortiGuard Security Advisory for vendor-provided technical context.

Detection Methods for CVE-2024-26007

Indicators of Compromise

Unexpected restarts, hangs, or unavailability of the FortiOS administrative web interface (httpsd / httpd processes).
Spikes of malformed HTTP requests to the management interface from a single or small set of external source IPs.
Loss of GUI access while the dataplane (firewall traffic forwarding) continues to function.

Detection Strategies

Monitor FortiOS system event logs for repeated administrative service crashes or daemon restart messages.
Inspect HTTP access logs on the management interface for malformed requests, unusual URI patterns, or oversized headers preceding service degradation.
Correlate management plane downtime with inbound HTTP traffic to identify exploitation attempts versus operational failures.

Monitoring Recommendations

Alert on availability loss of the FortiOS management interface using external synthetic checks against the admin URL.
Forward FortiOS syslog to a centralized logging platform and build detections for httpsd crash and restart events.
Track source IPs sending unauthenticated requests to the admin interface and threshold-alert on anomalous request rates.

How to Mitigate CVE-2024-26007

Immediate Actions Required

Identify all FortiGate devices running FortiOS 7.4.1 and prioritize them for upgrade per the FortiGuard Security Advisory.
Restrict access to the administrative interface to trusted management networks only, removing any WAN-side exposure.
Enforce trusthost configuration on admin accounts to limit which source addresses can reach the management service.

Patch Information

Fortinet addresses this issue in versions released after FortiOS 7.4.1. Consult the FortiGuard Security Advisory FG-IR-24-017 for the fixed release train and upgrade guidance specific to your hardware platform.

Workarounds

Disable HTTP/HTTPS administrative access on internet-facing interfaces and use a dedicated out-of-band management network.
Place the management interface behind a VPN or jump host so unauthenticated attackers cannot reach it directly.
Apply local-in-policy rules on FortiGate to permit management traffic only from defined administrator source ranges.

bash

# Restrict admin interface access via local-in-policy and trusthost
config system interface
    edit "wan1"
        set allowaccess ping
    next
end

config system admin
    edit "admin"
        set trusthost1 10.10.0.0 255.255.255.0
    next
end