Advisory Details

April 15th, 2026

Fortinet FortiWeb cat_cgi_paths Out-Of-Bounds Write Remote Code Execution Vulnerability

CVE ID	CVE-2026-40688
CVSS SCORE	8.8, AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
AFFECTED VENDORS	Fortinet
AFFECTED PRODUCTS	FortiWeb
VULNERABILITY DETAILS	This vulnerability allows remote attackers to execute arbitrary code on affected installations of Fortinet FortiWeb. Authentication is required to exploit this vulnerability. The specific flaw exists within the handling of HTTP requests. The issue results from the lack of proper validation of user-supplied data, which can result in a write past the end of an allocated buffer. 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-26-127
DISCLOSURE TIMELINE	2025-12-09 - Vulnerability reported to vendor 2026-04-15 - Coordinated public release of advisory 2026-04-15 - Advisory Updated
CREDIT	Jason McFadyen of Trend Research

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