CVE-2025-32756: Zero-Day Vulnerability in Multiple Fortinet Products Exploited in the Wild

Fortinet has observed threat actors exploiting CVE-2025-32756, a critical zero-day arbitrary code execution vulnerability which affects multiple Fortinet products including FortiVoice, FortiMail, FortiNDR, FortiRecorder and FortiCamera.

Background

On May 13th, Fortinet published a security advisory (FG-IR-25-254) for CVE-2025-32756, a critical arbitrary code execution vulnerability affecting multiple Fortinet products.

Analysis

CVE-2025-32756 is an arbitrary code execution vulnerability affecting multiple Fortinet products including FortiVoice, FortiMail, FortiNDR, FortiRecorder and FortiCamera. A remote unauthenticated attacker can send crafted HTTP requests in order to create a stack-based overflow condition which would allow for the execution of arbitrary code. This vulnerability was discovered by the Fortinet Product Security Team who observed threat activity involving a device running FortiVoice.

According to Fortinet, the threat actors operations included scanning the network, erasing system crashlogs and enabling ‘fcgi debugging’ which is used to log authentication attempts, including SSH logins. The ‘fcgi debugging’ option is not enabled by default and the Fortinet advisory recommends reviewing the setting as one possible indicator of compromise (IoC).

Historical Exploitation of Fortinet Devices

Fortinet vulnerabilities have historically been common targets for cyber attackers, and CVE-2025-32756 is the eighteenth Fortinet vulnerability to be added to the Cybersecurity and Infrastructure Security Agency’s (CISA) Known Exploited Vulnerabilities (KEV) list.

Proof of concept

At the time of writing this, no proof-of-concept (PoC) has been published for CVE-2025-32756. When a PoC is released, we expect attackers will incorporate this vulnerability in their attacks as Fortinet devices have been exploited by threat actors, including nation-state actors in the past.

Vendor response

Fortinet has provided a list of IoCs based on their observations of CVE-2025-32756. We recommend reviewing the list of IoCs and steps recommended by Fortinet to determine if your device may have been impacted.

Solution

The following table details the affected and fixed versions of Fortinet devices affected by CVE-2025-32756:

For users that are not able to immediately upgrade, Fortinet has provided a mitigation step; disabling the HTTP/HTTPS administrative interface. We recommend reviewing the Fortinet advisory for the latest information on workarounds and patched versions.

Identifying affected systems

A list of Tenable plugins for this vulnerability can be found on the individual CVE page for CVE-2025-32756 as they’re released. This link will display all available plugins for this vulnerability, including upcoming plugins in our Plugins Pipeline.

Additionally, customers can utilize Tenable Attack Surface Management to identify public facing assets running Fortinet devices by using the following subscription:

Get more information

• Fortinet FG-IR-25-254 Advisory

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