Fortinet FortiSandbox write_remote_backup_to_crontab cronValue Command Injection Remote Code Execution Vulnerability

September 9th, 2026
ZDI-26-645 ZDI-CAN-30081

CVE ID

CVE-2026-84387

CVSS Score

7.2 AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H

Affected Vendors

Fortinet

Affected Products

FortiSandbox

Vulnerability Details

This vulnerability allows remote attackers to execute arbitrary code on affected installations of Fortinet FortiSandbox. Authentication is required to exploit this vulnerability.

The specific flaw exists within the handling of the cronValue parameter passed to the write_remote_backup_to_crontab endpoint. The issue results from the lack of proper validation of a user-supplied string before using it to execute a system call. An attacker can leverage this vulnerability to execute code in the context of root.

Additional Details

Fortinet has issued an update to correct this vulnerability. More details can be found at:
https://fortiguard.fortinet.com/psirt/FG-IR-26-167

Disclosure Timeline

  • 2026-03-24 - Vulnerability reported to vendor
  • 2026-09-09 - Coordinated public release of advisory
  • 2026-09-09 - Advisory Updated

Credit

Jason McFadyen of TrendAI Security Research

Back to Advisories