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 via crafted HTTP requests.

Vulnerability class: Buffer Overflow

Published · last modified .

CVSS v3 metric

CVSS v3 base score 7.2 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.009 (57.5th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 58th percentile — 57.5% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2026-40688: fell from 0.064 to 0.009.

EPSS over last 30 days · oldest: 0.064 · newest: 0.009 · change: -0.056

Affected products

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-40688?
CVE-2026-40688 is a high-severity vulnerability in Fortinet Fortiweb, classified under Out-of-bounds Write. CVSS score: 7.2/10. Published 2026-04-14.
How severe is CVE-2026-40688?
High severity. CVSS v3 base score is 7.2 out of 10.