What is CVE-2026-40688?

CVE-2026-40688 is a medium-severity vulnerability in Fortinet Fortiweb, classified under Out-of-bounds Write. CVSS score: 6.7/10. Published 2026-04-14.

How severe is CVE-2026-40688?

Medium severity. CVSS v3 base score is 6.7 out of 10.

Buffer overflow in Fortinet Fortiweb

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 remote privileged attacker to execute arbitrary code or command…

Vulnerability class: Buffer Overflow

EPSS: 0.001 (31.0th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 6.7 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H/E:F/RL:O/RC:C.

Affected products

Fortinet Fortiweb — versions 8.0.0, 7.6.0, 7.4.0

Weakness classification (CWE)

CWE-787 — Out-of-bounds Write

References

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

Frequently asked questions

What is CVE-2026-40688?: CVE-2026-40688 is a medium-severity vulnerability in Fortinet Fortiweb, classified under Out-of-bounds Write. CVSS score: 6.7/10. Published 2026-04-14.
How severe is CVE-2026-40688?: Medium severity. CVSS v3 base score is 6.7 out of 10.