---
title: "CVE-2024-21338: Microsoft Windows Kernel Exposed IOCTL with Insufficient Access Control Vulnerability"
url: https://erroneo.us/security/cve/CVE-2024-21338/
description: "CVE-2024-21338 (Microsoft Windows): Exploited in the wild (CISA KEV). Windows Kernel Elevation of Privilege Vulnerability"
type: vulnerability-record
section: "Security Digest"
date_published: 2024-02-13
date_modified: 2026-08-10
publisher: erroneo.us
author: erroneo.us Security Desk
cve: "CVE-2024-21338"
kev: true
cvss: 7.8
epss: 0.5981
license: All rights reserved. Quote with attribution and a link.
---

# CVE-2024-21338: Microsoft Windows Kernel Exposed IOCTL with Insufficient Access Control Vulnerability

**Signal:** Exploited: patch now if you run it. CISA has confirmed exploitation in the wild. (Computed from CISA KEV, EPSS and CVSS; not an editorial verdict.)

## Should you act?

- Yes, if you run Microsoft Windows. CISA added this CVE to its Known Exploited Vulnerabilities catalog on 2024-03-04, which means there is reliable evidence of exploitation in the wild. US federal agencies must remediate by 2024-03-25 ; treat that as the outer limit, not the target. CISA also lists it as known to be used in ransomware campaigns .
- EPSS 59.8% , percentile 99: FIRST’s model estimates a 59.8% chance of exploitation activity in the next 30 days, higher than 99% of all scored CVEs (very high). EPSS is a probability, not a verdict.
- Needs local access needed. Lower urgency for most teams unless an attacker could already run code on the machine.

## What it is

Windows Kernel Elevation of Privilege Vulnerability

## Affected products (CVE record)

- Microsoft Windows 10 Version 1809: 10.0.17763.0 < 10.0.17763.5458
- Microsoft Windows 10 Version 1809: 10.0.0 < 10.0.17763.5458
- Microsoft Windows 10 Version 21H2: 10.0.19043.0 < 10.0.19044.4046
- Microsoft Windows 10 Version 22H2: 10.0.19045.0 < 10.0.19045.4046
- Microsoft Windows 11 version 21H2: 10.0.0 < 10.0.22000.2777
- Microsoft Windows 11 version 22H2: 10.0.22621.0 < 10.0.22621.3155
- Microsoft Windows 11 version 22H3: 10.0.22631.0 < 10.0.22631.3155
- Microsoft Windows 11 Version 23H2: 10.0.22631.0 < 10.0.22631.3155
- Microsoft Windows Server 2019: 10.0.17763.0 < 10.0.17763.5458
- Microsoft Windows Server 2019 (Server Core installation): 10.0.17763.0 < 10.0.17763.5458

## Severity

- microsoft CVSS 3.1: 7.8 `CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:F/RL:O/RC:C`

## Exploitation

- CISA KEV: added 2024-03-04; federal due date 2024-03-25. Known ransomware use: Known.
- CISA required action: Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.
- CISA SSVC assessment: exploitation active , automatable no , technical impact total .
- FIRST EPSS (model of 2026-10-21): 59.81% probability of exploitation activity in the next 30 days; percentile 99.

## Sources

- [Windows Kernel Elevation of Privilege Vulnerability](https://msrc.microsoft.com/update-guide/vulnerability/CVE-2024-21338)
- [CVE.org record CVE-2024-21338](https://www.cve.org/CVERecord?id=CVE-2024-21338)
- [NVD entry CVE-2024-21338](https://nvd.nist.gov/vuln/detail/CVE-2024-21338)
- [CISA Known Exploited Vulnerabilities catalog entry](https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2024-21338)
- [exploit-db.com](https://www.exploit-db.com/exploits/52275)
- [packetstorm.news](https://packetstorm.news/files/id/190586/)
- [decoded.avast.io](https://decoded.avast.io/janvojtesek/lazarus-and-the-fudmodule-rootkit-beyond-byovd-with-an-admin-to-kernel-zero-day/)

---
Source page: https://erroneo.us/security/cve/CVE-2024-21338/ · Security Digest: https://erroneo.us/security/ · More: https://erroneo.us/llms.txt