Summary
| Vulnerability Name | FortiSandbox Path Traversal (CVE-2026-39813) |
| Released on | April 23, 2026 |
| Affected Component | FortiSandbox |
| Affected Version | 5.0.0 <= FortiSandbox <= 5.0.5 4.4.0 <= FortiSandbox <= 4.4.8 |
| Vulnerability Type | Path traversal |
| Exploitation Condition | 1. User authentication: not required. 2. Preconditions: default configurations. 3. Trigger mode: remote. |
| Impact | Exploitation difficulty: easy. Unauthorized attackers can exploit this vulnerability to disclose sensitive information. Severity: critical. This vulnerability may lead to sensitive information disclosure. |
| Official Solution | Available |
About the Vulnerability
Component Introduction
Fortinet FortiSandbox is an advanced sandbox technology designed to detect and defend against unknown malware and attacks through dynamic analysis. It can effectively simulate attack environments and capture potential threats to enhance network security.
Vulnerability Description
On April 23, 2026, Sangfor FarSight Labs received notification of the path traversal vulnerability in FortiSandbox (CVE-2026-39813), classified as critical in threat level.
Specifically, there is a path traversal vulnerability in FortiSandbox V5.0.0 to V5.0.5 and V4.4.0 to V4.4.8 due to improper input validation. Attackers can exploit this vulnerability to escalate their privileges by carefully crafting path traversal requests.
Affected Versions
The following FortiSandbox EMS versions are affected:
5.0.0 <= FortiSandbox <= 5.0.5
4.4.0 <= FortiSandbox <= 4.4.8
Solutions
Remediation Solutions
Official Solutions
The latest versions have been officially released to fix the vulnerability. Affected users are advised to update FortiSandbox whose version ranges from 5.0.0 to 5.0.5 to 5.06 or later, and FortiSandbox whose version ranges from 4.4.0 to 4.4.8 to 4.49 or later.
Temporary Solutions
- Disable unused functional modules to reduce attack entry points.
- Follow the principle of least privilege to strictly control the scope of permissions for sensitive operations.
- Do not expose services to the Internet unless necessary, to limit the access sources to trusted ranges.
- Regularly update the system and components to secure versions so that known vulnerabilities can be patched at the earliest opportunity.
Sangfor Solutions
Vulnerability Monitoring
The following Sangfor services support CVE-2026-39813 vulnerability monitoring, and can quickly identify affected assets and the impact scope in business scenarios in real time through traffic collection:
- Athena Network Detection and Response (NDR): The corresponding monitoring solution will be released on May 06, 2026. The rule ID is 11220421.
- Athena Managed Detection and Response (MDR): The corresponding monitoring solution will be released on May 06, 2026. The rule ID is 11220421. In this case, make sure that Athena MDR is integrated with Athena NDR.
- Athena Extended Detection and Response (XDR): The corresponding monitoring solution will be released on May 06, 2026. The rule ID is 11220421.
Vulnerability Prevention
The following Sangfor services can effectively block CVE-2026-39813 exploits:
- Athena Next-Generation Firewall (NGFW): The corresponding prevention solution will be released on May 06, 2026. The rule ID is 11220421.
- Sangfor Web Application Firewall (WAF): The corresponding prevention solution will be released on May 06, 2026. The rule ID is 11220421.
- Athena MDR: The corresponding prevention solution will be released on May 06, 2026. The rule ID is 11220421. In this case, make sure that Athena MDR is integrated with Athena NGFW.
- Athena XDR: The corresponding prevention solution will be released on May 06, 2026. The rule ID is 11220421. In this case, make sure that Athena XDR is integrated with Athena NGFW.
Timeline
On April 23, 2026, Sangfor FarSight Labs received notification of the path traversal vulnerability in FortiSandbox (CVE-2026-39813).
On April 24, 2026, Sangfor FarSight Labs released a vulnerability alert.
Reference
https://fortiguard.fortinet.com/psirt/FG-IR-26-112
Learn More
Sangfor FarSight Labs researches the latest cyber threats and unknown zero-day vulnerabilities, alerting customers to potential dangers to their organizations, and providing real-time solutions with actionable intelligence. Sangfor FarSight Labs works with other security vendors and the security community at large to identify and verify global cyber threats, providing fast and easy protection for customers.
