How severe is CVE-2026-40688?

CVE-2026-40688 has a CVSS 3.x base score of 7.2, rated high severity. It is exploitable over network with low attack complexity, requires high privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2026-40688 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 6% (93rd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-40688?

CVE-2026-40688 affects Fortinet Fortiweb. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-40688?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

Does CVE-2026-40688 have an EU (EUVD) identifier?

Yes. CVE-2026-40688 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-22808.

When was CVE-2026-40688 published?

CVE-2026-40688 was published on 2026-04-14 and last updated on 2026-06-17.

CVE-2026-40688

CVE-2026-40688 is a high-severity vulnerability in Fortinet Fortiweb with a CVSS 3.x base score of 7.2. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-787.

Key facts

Severity: High (CVSS 3.x base score 7.2)
EPSS exploit prediction: 6% (93rd percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-22808
Weakness: CWE-787
Affected product: Fortinet Fortiweb
Published: 2026-04-14
Last modified: 2026-06-17

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.

Frequently asked questions

What is 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.
How severe is CVE-2026-40688?: CVE-2026-40688 has a CVSS 3.x base score of 7.2, rated high severity. It is exploitable over network with low attack complexity, requires high privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2026-40688 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 6% (93rd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-40688?: CVE-2026-40688 affects Fortinet Fortiweb. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-40688?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
Does CVE-2026-40688 have an EU (EUVD) identifier?: Yes. CVE-2026-40688 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-22808.
When was CVE-2026-40688 published?: CVE-2026-40688 was published on 2026-04-14 and last updated on 2026-06-17.

References

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

Affected products (1)

cpe:2.3:a:fortinet:fortiweb:*:*:*:*:*:*:*:*

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