Key points
- FortiGuard identifies a use of hard-coded cryptographic keys in FortiSandbox API.
- The flaw allows unauthenticated attackers to access specific endpoints via HTTP.
- The vulnerability is rated 4.9 on the CVSS v3 scale by FortiGuard PSIRT.
FortiGuard Labs has identified an authentication bypass vulnerability in the Fabric API of FortiSandbox and FortiSandbox Cloud. The issue stems from the use of a hard-coded cryptographic key, classified as CWE-321. According to the official advisory, this flaw allows an unauthenticated attacker to access certain API endpoints by sending specially crafted HTTP requests. The vendor revised the advisory on October 13, 2026, to reflect the current status of the finding.
By the numbers
- 4.9: The CVSS v3 base score assigned by FortiGuard to the authentication bypass flaw.
- 321: The CWE identifier for the use of hard-coded cryptographic keys causing the issue.
- 179: The sequential number of the FortiGuard PSIRT advisory FG-IR-26-179.
What the figures mean
A CVSS v3 score of 4.9 indicates a medium severity vulnerability. FortiGuard rates this specifically as a use of hard-coded cryptographic keys. The advisory states that the flaw permits unauthenticated access to some endpoints. It does not claim full system compromise or arbitrary code execution. The impact is limited to the endpoints reachable via the crafted HTTP requests. Analysts should note that the flaw exists in both on-premises FortiSandbox and FortiSandbox Cloud environments. The vendor has not disclosed a patch or mitigation in this advisory text.
What to watch
Security teams should monitor network traffic for unusual HTTP requests to FortiSandbox API endpoints. Since the flaw involves hard-coded keys, any request using that specific key without proper authentication is suspicious. FortiGuard advises that the vulnerability affects the Fabric API specifically. Organizations should review their firewall rules to restrict access to these API endpoints. The advisory was revised in October 2026, suggesting ongoing vendor assessment. No exploit code or active abuse has been confirmed by the source material.
Infection and persistence in general
API authentication flaws typically allow attackers to bypass login screens entirely. Threat actors often discover these endpoints through documentation or network scanning. Once access is gained, they may exfiltrate data or modify configurations. Persistence is usually achieved by creating new administrative accounts or altering API keys. Analysts examine server logs for unauthenticated requests to sensitive endpoints. They also check for unusual outbound traffic from the API server. Teams should verify that all API calls require valid, rotating credentials.
What to do and how to stay safe: FortiSandbox
- Restrict network access to FortiSandbox API endpoints to trusted internal IPs only.
- Monitor logs for unauthenticated HTTP requests to Fabric API endpoints.
- Verify that no hard-coded keys are exposed in configuration files or scripts.
- Contact FortiGuard support for guidance on mitigating the unauthenticated access risk.
Step-by-step guide: Patch Management Implementation: A Step-by-Step Rollout Plan
General security guidance from the Sandbox Gazette newsroom. It is not confirmed advice from the organisations named in this story.
Frequently asked questions
What is the CVSS score for the FortiSandbox API bypass?
FortiGuard assigns a CVSS v3 score of 4.9 to this authentication bypass vulnerability.
Which products are affected by this hard-coded key flaw?
The flaw affects both FortiSandbox and FortiSandbox Cloud API services.
Is there a patch available for this vulnerability?
The source material does not confirm the availability of a patch or update.
