9.6-rated FortiSandbox Bypass Lets Attackers Skip Login to Run Commands

Fortinet released advisory FG-IR-26-185 on October 13, 2026, addressing a critical authentication bypass in its FortiSandbox graphical user interface. The flaw, tracked as CVE-2026-107656, allows remote attackers to access protected functions without valid credentials. According to Cyber Security News, the issue affects both standalone FortiSandbox appliances and selected FortiSandbox PaaS releases. Fortinet assigns a CVSSv3 score of 9.6 to the vulnerability, reflecting its high potential impact on systems.

Which environments are exposed?

Organizations running FortiSandbox versions 5.0.0 through 5.0.6 are vulnerable and must upgrade to version 5.0.7 or later. Similarly, deployments using versions 4.4.0 through 4.4.9 require an update to version 4.4.10 or later. The FortiSandbox 5.2 branch is not affected by this specific flaw. For cloud deployments, FortiSandbox PaaS versions 5.0.0 through 5.0.6 need the same 5.0.7 upgrade. All PaaS 4.4 versions are affected, with Fortinet directing customers to migrate to a fixed release. PaaS 5.2 remains unaffected.

How does the attack work?

The weakness is classified as CWE-288, an authentication bypass using an alternate path or channel. According to GBHackers, improper access control and session management in the GUI create a route around normal authentication checks. A remote attacker can send crafted HTTP requests to exploit this gap. The CVSS vector indicates the attack is network-accessible, requires low complexity, needs no privileges, and demands no user interaction. This means exploitation does not depend on stealing existing account credentials or tricking an administrator into clicking a link.

Is there evidence of active exploitation?

Fortinet’s advisory marks known exploitation as “No,” meaning there is no confirmed evidence that attackers have used this vulnerability in real-world attacks yet. The company credits Adham El Karn of its Product Security team for discovering the issue internally. Jason McFadyen of TrendAI Research is acknowledged for responsible disclosure. The advisory does not provide specific request paths, exploit payloads, or detailed attack chains. Security teams should not assume this flaw shares the same exploit method as earlier FortiSandbox authentication bypass vulnerabilities, which involved different components.

What remediation steps are required?

Administrators must upgrade vulnerable deployments to the specified fixed versions. For version 4.4 users, moving to 4.4.10 is required. For version 5.0 users, upgrading to 5.0.7 or later resolves the issue. Fortinet warns that fixes for a separate, previously disclosed sensitive data exposure vulnerability in the web interface do not protect against this new authentication bypass. Administrators should verify their exact product and release against the new advisory before selecting an upgrade to avoid confusing separate security fixes. No virtual patch is listed for this vulnerability.

Detection notes

Security operations teams should monitor for unusual HTTP traffic patterns targeting the FortiSandbox management interface. Look for requests that bypass standard login flows or access protected endpoints without prior authentication tokens. Check for sudden spikes in unauthorized command execution logs within the sandbox environment. If anomalous behavior is detected, isolate the affected appliance from the network immediately to prevent further compromise.

Review access logs for any successful sessions initiated without valid credentials. Validate system integrity by checking for unexpected changes to configuration files or user permissions. Correlate these indicators with known threat intelligence feeds to assess the scope of potential exposure. Ensure that all monitoring tools are configured to alert on deviations from baseline traffic patterns for critical management ports.

What to do and how to stay safe: Fortinet

• Inventory all FortiSandbox appliances and PaaS instances to identify those running versions 4.4.0–4.4.9 or 5.0.0–5.0.6.
• Prioritize upgrades to version 4.4.10 or 5.0.7, verifying that version 5.2 deployments are already secure against this specific flaw.
• Monitor network traffic to the FortiSandbox GUI for unauthorized access attempts or unusual HTTP requests that bypass authentication.
• Review system logs for any signs of unauthorized command execution or changes to configuration settings that occurred outside of maintenance windows.

Step-by-step guide: Patch Management Checklist: Secure Systems Without Breaking Them

General security guidance from the Firewall Scoop newsroom. It is not confirmed advice from the organisations named in this story.

Frequently asked questions

What is the severity rating for CVE-2026-107656?

Fortinet assigns a CVSSv3 score of 9.6 to this vulnerability, classifying its severity as critical due to high impacts on confidentiality, integrity, and availability.

Does the fix for the previous sensitive data exposure vulnerability protect against this new bypass?

No, administrators should not treat fixes for the previous sensitive data exposure vulnerability as protection against this new authentication bypass flaw.

Are FortiSandbox 5.2 deployments affected by this vulnerability?

No, Fortinet confirms that both FortiSandbox 5.2 appliances and FortiSandbox PaaS 5.2 are not affected by CVE-2026-107656.