CVE-2024-46668 is a denial of service (DoS) vulnerability identified in multiple versions of Fortinet's FortiOS, specifically versions 6.4.0 through 6.4.15, 7.0.0 through 7.0.15, 7.2.0 through 7.2.8, and 7.4.0 through 7.4.4. The root cause is an allocation of resources without limits or throttling (CWE-770), which allows an unauthenticated remote attacker to consume all available system memory by uploading multiple large files. This memory exhaustion can lead to system instability, crashes, or reboots, effectively denying legitimate users access to the device and its services. The vulnerability requires no authentication or user interaction, increasing the risk of automated or widespread exploitation. The CVSS v3.1 base score is 7.1, reflecting high severity primarily due to the impact on availability (A:H) and the ease of exploitation (AV:N/AC:L/PR:N/UI:N). No confidentiality or integrity impacts are noted. Although no public exploits have been reported yet, the vulnerability’s characteristics suggest it could be weaponized for targeted or opportunistic DoS attacks. Fortinet devices are widely used in enterprise and service provider networks for firewalling, VPN, and security gateway functions, making this vulnerability particularly concerning for network availability and operational continuity. The lack of patch links indicates that fixes may be pending or recently released, emphasizing the need for vigilance and timely remediation.

For European organizations, the primary impact of CVE-2024-46668 is on availability. FortiOS devices often serve as critical network security infrastructure, including firewalls, VPN gateways, and unified threat management appliances. Successful exploitation can cause device crashes or reboots, leading to network outages, loss of connectivity, and disruption of business operations. This can affect sectors reliant on continuous network availability such as finance, healthcare, telecommunications, and government services. The unauthenticated nature of the attack vector means attackers can launch DoS attempts from external networks without prior access, increasing exposure. Additionally, denial of service against perimeter devices can open windows for secondary attacks or impede incident response capabilities. While no confidentiality or integrity breaches are indicated, the operational impact and potential cascading effects on dependent systems make this vulnerability a significant risk. Organizations with large Fortinet deployments or those in critical infrastructure sectors should consider this a priority threat.

1. Monitor Fortinet advisories closely and apply security patches or firmware updates as soon as they are released to address CVE-2024-46668. 2. Implement network-level controls to limit or throttle large file uploads to FortiOS devices, such as rate limiting or file size restrictions at perimeter gateways or proxies. 3. Employ intrusion detection and prevention systems (IDS/IPS) to detect anomalous traffic patterns consistent with large file upload floods targeting FortiOS management or upload interfaces. 4. Restrict access to FortiOS management interfaces and upload endpoints to trusted IP addresses or VPNs to reduce exposure to unauthenticated attackers. 5. Conduct regular capacity planning and resource monitoring on FortiOS devices to detect early signs of memory exhaustion or abnormal resource consumption. 6. Develop and test incident response plans specifically for FortiOS device outages to minimize downtime and recovery time in case of exploitation. 7. Consider network segmentation to isolate critical FortiOS devices and limit the blast radius of potential DoS attacks. 8. Engage with Fortinet support for guidance on interim mitigations if patches are not yet available.