External risk intelligence

Fortinet FortiSandbox Authentication Bypass Leads to Unauthorized Code Execution

CVE advisorySeverity: CRITICAL (CVSS 9.8)

CVE-2026-107656

FortiSandbox is an appliance-based security solution designed for network analysis and traffic inspection. These devices are frequently deployed at the network edge or in segments where they are exposed to inbound traffic for analysis and management, making them likely to be reachable from the network or internet in typical enterprise security deployments.

Authentication Bypass

Halo Surface Signal: 4 out of 5 — likely to be public-facing.

External exposure likelihood

Horizon Alert

Summary of the vulnerability and why it matters

An authentication bypass vulnerability in Fortinet FortiSandbox products could allow attackers to execute unauthorized code or commands through specially crafted HTTP requests. This issue affects multiple versions of FortiSandbox and its PaaS offerings. The main concern is confirming relevance and exposure given the nature of the vulnerability.

Bypass login to run unauthorized commands.
It impacts critical network security analysis tools.
Verify if your FortiSandbox is affected.

Attack Path

How an attacker could exploit the issue

An attacker could bypass authentication by sending specially crafted HTTP requests to an exposed FortiSandbox appliance. This bypass targets a vulnerability in how the appliance handles certain network traffic, potentially allowing unauthorized code or commands to be executed.

Attacker sends crafted HTTP requests.
Vulnerability in alternate HTTP path is triggered.
Unauthorized code or commands may be executed.

Live Threat

Current exploitation, exposure, and threat context

An authentication bypass vulnerability in Fortinet FortiSandbox products could allow an attacker to execute unauthorized code or commands by sending specially crafted HTTP requests. This occurs when an attacker can exploit an alternate path or channel to bypass authentication controls.

Unauthorized code execution.
Exploiting alternate HTTP paths.
System compromise.

Operational Fix

Recommended remediation, mitigation, and detection steps

The primary responsibility for addressing this vulnerability lies with the Platform/Infrastructure teams managing FortiSandbox deployments, in coordination with Security Operations (SecOps). The first practical step is to identify all deployed FortiSandbox instances, confirm their network exposure and business criticality, and then prioritize remediation based on this assessment.

Platform/Infrastructure teams own remediation.
Verify network exposure and asset criticality.
Plan coordinated patching or mitigation.

Supplementary metadata

CVSS vector

Validate whether this threat affects your internet-facing exposure.

Halo Threat Intelligence helps prioritize remediation with Halo Surface Signal and H/A/L/O context. Start exposure validation with a free external attack surface trial.

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Frequently asked questions

What is Fortinet FortiSandbox?

FortiSandbox is a specialized security appliance used by organizations to perform deep inspection of network traffic and files. It acts as an analysis engine to identify and block malicious activity by detonating suspicious content in a safe, isolated environment. It is a critical component of a layered network defense strategy, often positioned to inspect traffic entering or moving within an enterprise.

What does CWE-288 mean for CVE-2026-107656?

CWE-288 refers to Authentication Bypass Using an Alternate Path or Channel. In the context of this CVE, it means the software contains a logic error where it accepts an alternative way to interact with the system that fails to verify the user's identity properly. Because the security checks are bypassed, an unauthorized user can interact with the system as if they were a legitimate administrator, potentially allowing them to run arbitrary commands.

How is this authentication bypass triggered?

An attacker triggers this vulnerability by sending specifically crafted HTTP requests to the target device. The system incorrectly processes these requests through an unintended path, granting access without requiring a valid login. It is important to note that standard, legitimate administrative tasks performed through authorized interfaces do not trigger this flaw; the vulnerability specifically relies on exploiting the improper handling of these malicious, non-standard request patterns.

Is my FortiSandbox likely to be reachable by an attacker?

According to Halo Surface Signal, FortiSandbox appliances are often deployed at network edges or in segments that handle inbound traffic for inspection. This common architectural placement means your instance is more likely to be reachable from the network or the internet. Because the attack vector is network-based, any device with a management or analysis interface accessible to the broader network faces a higher risk of being targeted.

What should I do if I use FortiSandbox?

Your first step is to conduct an inventory to identify all instances of FortiSandbox currently running in your environment. Once identified, evaluate which of these are reachable from your network perimeter versus those in isolated segments. Coordinate with your infrastructure and security teams to review the affected versions and establish a plan for applying security updates or configuration changes as soon as they become available.

References

fortiguard.fortinet.com/psirt/FG-IR-26-185

Written by Nicholas Merritt

Nicholas Merritt is VP of Security Solutions at Halo Security. With more than 25 years across application security, vulnerability prioritization, and offensive security, he helps teams translate threat data into practical exposure validation and remediation focus. He authors Halo Threat Intelligence CVE advisories using Halo Surface Signal and H/A/L/O context to prioritize internet-facing risk.