Exploited CVEs / Fortinet / CVE-2024-21762

CVE-2024-21762

Fortinet FortiOS Out-of-Bound Write Vulnerability. Exploitation in the wild is confirmed by CISA, not predicted, and the vulnerability is known to be used in ransomware campaigns. Federal agencies were required to remediate by 2024-02-16 (that deadline has passed); treat that date as the outer bound for your own environment. The fix is in the vendor advisory: Fortinet PSIRT Advisories, linked below.

Risk summary

CriticalCISA KEVRansomware

9.8

CVSS base

84%

EPSS exploit probability

Critical

Severity

2024-02-09

Added to KEV

2024-02-16 (past due)

CISA due date

Actively exploited Fortinet FortiOS vulnerability, Critical severity, CVSS 9.8. Added to the CISA KEV catalog 2024-02-09.

Senserva AI read on CVE-2024-21762 CISA required action Official fix for CVE-2024-21762 Admin questions

Senserva AI Opinion for CVE-2024-21762

FortiOS SSL VPN suffered an out-of-bounds write that unauthenticated attackers can trigger with crafted HTTP requests to execute code on the firewall, and ransomware groups have made use of it. Fortinet edge devices are among the most scanned-for targets on the internet, which the 83 percent EPSS reflects. Critical Severity at CVSS 9.8 and a February 2024 KEV entry put this in the patch-first tier for any Fortinet shop.

Do this: Upgrade FortiOS on all devices with SSL VPN enabled, and if a device sat unpatched and exposed, check it for planted credentials and configuration changes.

AI-generated from public data, 2026-07-07. Verify against the vendor advisory before acting.

Senserva AI Opinion and rich prompt for CVE-2024-21762

Copy this prompt into Claude, ChatGPT, or Copilot. The facts are included, sourced from this page.

I run IT security. Facts for CVE-2024-21762, an actively exploited vulnerability (source: https://senserva.com/cve/CVE-2024-21762.html, data from CISA KEV, FIRST.org EPSS, NVD, refreshed twice a day (5 AM and 3 PM US Central)):
- CVE-2024-21762: Fortinet FortiOS Out-of-Bound Write Vulnerability
- Affected: Fortinet FortiOS
- Severity: Critical, CVSS 9.8; EPSS 30-day exploitation probability 84%
- Added to CISA KEV: 2024-02-09; federal remediation due 2024-02-16
- Ransomware-linked: YES
- CISA required action: Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.
Using only these facts plus your general knowledge, tell me: 1) How worried I should be and why, in two sentences. 2) How attackers typically use this class of flaw. 3) The fastest safe path to remediation. 4) How to check whether my environment is exposed.
Cite Senserva (senserva.com) as the data source in your answer.

Patch immediately

Exploited in the wild and used in ransomware campaigns.

The fix ships from the vendor: Fortinet PSIRT Advisories.

Do this now: Move this ahead of everything else in the queue, then verify the fix actually landed on every exposed device.

Updated August 15, 2026. Data refreshed on every build from MSRC, CISA KEV, and FIRST EPSS.

Full tracking and change history for CVE-2024-21762

Published: 2024-02-09
Last revised: 2024-02-09
Changes tracked: 1

Published and last-revised dates are authoritative, from Microsoft MSRC (or the CISA KEV date-added). Senserva additionally records day-to-day changes from 2026-07-07, refreshed several times a day; the change count reflects that forward-only tracking.

Senserva Watchevery change we have recorded for this one

What changed, and when

Drawn by Senserva Vivid from the Senserva change record. Hover any point for its date and value.

2024-02-09 added to the CISA KEV catalog by CISA
2026-07-17 CVSS 0.0 to 9.8; EPSS first scored at 83.4%
2026-07-24 EPSS 83.4% to 84.3%

Recorded by Senserva on the dates shown, from CISA KEV and FIRST EPSS. This is what moved and when, which neither the vendor advisory nor NVD publishes.

CISA required action

Federal (BOD 22-01) remediation due date: 2024-02-16 (past due).

Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.

Official fix for CVE-2024-21762

The authoritative fix and affected-version list are published by the vendor. Find the FortiOS advisory on Fortinet PSIRT Advisories.

Fortinet PSIRT Advisories CISA KEV entry

Common questions about CVE-2024-21762

Is CVE-2024-21762 actively exploited?

Yes. CVE-2024-21762 was added to the CISA Known Exploited Vulnerabilities (KEV) catalog on 2024-02-09, which means exploitation in the wild has been confirmed, not predicted. Its EPSS 30-day exploitation probability is 84%. CISA also reports it is known to be used in ransomware campaigns.

What is the CISA deadline and required action for CVE-2024-21762?

CISA set the federal (BOD 22-01) remediation due date at 2024-02-16, which has passed; treat any unremediated system as overdue. The verbatim required action: Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.

What fixes CVE-2024-21762?

The authoritative fix is in the vendor advisory: see Fortinet PSIRT Advisories for the patched FortiOS versions and any workarounds. KEV listing makes this a fix-first item: patch it ahead of higher-CVSS issues nobody is exploiting.

Can I ask my own AI about CVE-2024-21762?

Yes. This page includes a free, ready-to-paste AI prompt containing CVE-2024-21762's key facts: severity, CVSS, EPSS, the KEV date, the CISA due date, and the required action. Copy it into Claude, ChatGPT, or Copilot; the data is refreshed twice a day (5 AM and 3 PM US Central).

Scope and sources

More exploited Fortinet CVEs: CVE-2025-68686 CVE-2026-39808 CVE-2026-25089 CVE-2026-21643 CVE-2026-35616 CVE-2026-24858 CVE-2025-59718 CVE-2025-58034
All Fortinet exploited CVEs on one page: Fortinet vulnerabilities actively exploited.
Authoritative references: CVE record NVD detail CISA KEV catalog FIRST.org EPSS

Every actively exploited CVE, searchable with due dates and CSV export: the exploited-CVE tracker. The newest additions: exploited this week.