CVE-2026-40688: An out-of-bounds write vulnerability [CWE-787] vulnerability in Fortinet FortiWeb 8.0.0 through 8.0.3, FortiWeb 7.6.0 through 7.6.6, FortiWeb 7.4.0 through 7.4.11 may allow a…

High severity · published Apr 14, 2026

CVE-2026-40688

An out-of-bounds write vulnerability [CWE-787] vulnerability in Fortinet FortiWeb 8.0.0 through 8.0.3, FortiWeb 7.6.0 through 7.6.6, FortiWeb 7.4.0 through 7.4.11 may allow a…

7.2

CVSS

6.4%

EPSS

On KEV

Description

An out-of-bounds write vulnerability [CWE-787] vulnerability in Fortinet FortiWeb 8.0.0 through 8.0.3, FortiWeb 7.6.0 through 7.6.6, FortiWeb 7.4.0 through 7.4.11 may allow a remote privileged attacker to execute arbitrary code or command via crafted HTTP requests.

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H

Attack vector

Network

Complexity

Low

Privileges

High

User interaction

None

Confidentiality

High

Integrity

High

Availability

High

Scope

Unchanged

Exploitation

Is it being used?

Exploit prediction (EPSS)6.4% · higher than 94% of CVEs

Exploited in the wildNo evidence yet

CISA KEVNot listed

Ransomware campaign useNot known

Affected products

Which versions

FortiWeb · Fortinet

8.0.0 through 8.0.3; 7.6.0 through 7.6.6; 7.4.0 through 7.4.11 · source: vendor, NVD

In the news

VulnerabilityCritical

ZDI-26-266: Fortinet FortiWeb cat_cgi_paths Out-Of-Bounds Write Remote Code Execution Vulnerability

This vulnerability allows remote attackers to execute arbitrary code on affected installations of Fortinet FortiWeb. Authentication is required to exploit this vulnerability. The ZDI has assigned a CVSS rating of 8.8. The following CVEs are assigned: CVE-2026-40688.

CVE-2026-40688

Apr 15, 2026·Zero Day Initiative

Affected product

FortiWeb

Fortinet

All FortiWeb CVEs

References

NVD

https://nvd.nist.gov/vuln/detail/CVE-2026-40688

CVE.org

https://www.cve.org/CVERecord?id=CVE-2026-40688

Vendor Advisory

https://fortiguard.fortinet.com/psirt/FG-IR-26-127