No exploitation reportedFix available

CVE-2021-24018

Q: Is CVE-2021-24018 actively exploited?

Active exploitation of CVE-2021-24018 has not been confirmed. Its EPSS score was 1.0% on 2026-10-23, the estimated probability of exploitation in the next 30 days.

Q: What is the CVSS score for CVE-2021-24018?

CVE-2021-24018 has a CVSS v3 base score of 8.8 (HIGH severity), with vector string CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

No exploitation reported by the sources we read.

Published2021-08-04
Fixed in6.4.7 · 6.2.10
WeaknessCWE-787

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

A buffer underwrite vulnerability in the firmware verification routine of FortiOS before 7.0.1 may allow an attacker located in the adjacent network to potentially execute arbitrary code via a specifically crafted firmware image.

Timeline

dates in UTC

2021-08-0415:15CVE publishedNVD

Observed activity

isMalicious corpus · updated 2026-10-23 21:37 UTC

Indicators tagged with this CVE, per day0 indicators over 7 days

Block these indicators

Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2021-24018?format=txt
CSV export: https://api.ismalicious.com/edl/cve/CVE-2021-24018?format=csv
TAXII collection of exploited CVEs
The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD

Fortinet FortiOS

Branch	Affected	Fixed in	Source
6.4	≥ 6.4.0, < 6.4.7	6.4.7	NVD
6.2	< 6.2.10	6.2.10	NVD
7.0	= 7.0.0	no fix published	NVD

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Fix

Update Fortinet FortiOS to 6.4.7 · 6.2.10

Advisories and patches

fortiguard.comVendor Advisory

Detection

Nuclei template: none so far
Exploit-DB: no entry
Proof-of-concept repositories: none listed

Sources

CISA-ADPSSVC decisionnone2024-10-23
OpenCVESSVC decisionnone—
CNACVSS 3.14.3read 2026-10-23
NVDCVSS 3.18.8read 2026-10-23
NVDCVSS 2.05.8read 2026-10-23
NVDweakness (CWE)CWE-787read 2026-10-23
FIRST EPSSEPSS score1.0 %2026-10-23

Technical details

CVSS v3 Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Published: 2021-08-04
Last Modified: 2026-06-17
NVD status: Modified

Frequently asked questions

What is CVE-2021-24018?

Is CVE-2021-24018 actively exploited?

Active exploitation of CVE-2021-24018 has not been confirmed. Its EPSS score was 1.0% on 2026-10-23, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2021-24018?

CVE-2021-24018 has a CVSS v3 base score of 8.8 (HIGH severity), with vector string CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

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