Fortinet FortiOS/FortiProxy HTTP Header response splitting

Summaryinfo

A vulnerability was found in Fortinet FortiOS and FortiProxy. It has been rated as critical. This issue affects some unknown processing of the component HTTP Header Handler. The manipulation leads to response splitting. This vulnerability is referenced as CVE-2024-54021. Remote exploitation of the attack is possible. No exploit is available.

Detailsinfo

A vulnerability was found in Fortinet FortiOS and FortiProxy (version unknown) and classified as critical. This issue affects an unknown function of the component HTTP Header Handler. The manipulation with an unknown input leads to a response splitting vulnerability. Using CWE to declare the problem leads to CWE-113. The product receives data from an HTTP agent/component (e.g., web server, proxy, browser, etc.), but it does not neutralize or incorrectly neutralizes CR and LF characters before the data is included in outgoing HTTP headers. Impacted is integrity, and availability. The summary by CVE is:

An improper neutralization of crlf sequences in http headers ('http response splitting') in Fortinet FortiOS 7.2.0 through 7.6.0, FortiProxy 7.2.0 through 7.4.5 allows attacker to execute unauthorized code or commands via crafted HTTP header.

It is possible to read the advisory at fortiguard.fortinet.com. The identification of this vulnerability is CVE-2024-54021 since 11/27/2024. The exploitation is known to be easy. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. The technical details are unknown and an exploit is not publicly available. The pricing for an exploit might be around USD $0-$5k at the moment (estimation calculated on 08/08/2025).

The vulnerability scanner Nessus provides a plugin with the ID 214075 (Fortinet Fortigate File-Filter Bypass in Explicit Web Proxy Policy (FG-IR-24-282)), which helps to determine the existence of the flaw in a target environment.

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

The vulnerability is also documented in the databases at Tenable (214075) and EUVD (EUVD-2024-52244). Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Productinfo

Type

• Firewall Software

Vendor

• Fortinet

Name

• FortiOS
• FortiProxy

License

• commercial

Website

• Vendor: https://www.fortinet.com/

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Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

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