Windows Kernel Elevation of Privilege Vulnerability (CVE-2024-21338)
Published Last modified In CISA KEV since Sources: pwn.watch, CVE.org
What is affected, what to do
Windows Kernel Elevation of Privilege Vulnerability
The vulnerability is being actively exploited; treat it as a priority. CISA lists it as used in ransomware campaigns. Update Microsoft Windows 10 Version 1809 to version 10.0.17763.5458, Microsoft Windows 10 Version 21H2 to version 10.0.19044.4046, Microsoft Windows 10 Version 22H2 to version 10.0.19045.4046. Immediate actions, mitigation and detection rules are in the runbook below.
- Affected
- Microsoft Windows 10 Version 1809
lt 10.0.17763.0..10.0.17763.5458 - Microsoft Windows 10 Version 21H2
lt 10.0.19043.0..10.0.19044.4046 - Microsoft Windows 10 Version 22H2
lt 10.0.19045.0..10.0.19045.4046 - Microsoft Windows 11 version 21H2
lt 10.0.0..10.0.22000.2777 - Microsoft Windows 11 version 22H2
lt 10.0.22621.0..10.0.22621.3155 - Microsoft Windows 11 version 22H3
lt 10.0.22631.0..10.0.22631.3155 - Microsoft Windows 11 Version 23H2
lt 10.0.22631.0..10.0.22631.3155 - Microsoft Windows Server 2019
lt 10.0.17763.0..10.0.17763.5458 - Microsoft Windows Server 2019 (Server Core installation)
lt 10.0.17763.0..10.0.17763.5458 - Microsoft Windows Server 2022
lt 10.0.20348.0..10.0.20348.2322 - Microsoft Windows Server 2022, 23H2 Edition (Server Core installation)
lt 10.0.25398.0..10.0.25398.709
- Microsoft Windows 10 Version 1809
- Fixed in
- Microsoft Windows 10 Version 1809
10.0.17763.5458 - Microsoft Windows 10 Version 21H2
10.0.19044.4046 - Microsoft Windows 10 Version 22H2
10.0.19045.4046 - Microsoft Windows 11 version 21H2
10.0.22000.2777 - Microsoft Windows 11 version 22H2
10.0.22621.3155 - Microsoft Windows 11 version 22H3
10.0.22631.3155 - Microsoft Windows 11 Version 23H2
10.0.22631.3155 - Microsoft Windows Server 2019
10.0.17763.5458 - Microsoft Windows Server 2019 (Server Core installation)
10.0.17763.5458 - Microsoft Windows Server 2022
10.0.20348.2322 - Microsoft Windows Server 2022, 23H2 Edition (Server Core installation)
10.0.25398.709
- Microsoft Windows 10 Version 1809
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Metrics
7.8
Priority
XIEM Effective CVSS: highest available CVSS rating from NVD and vendor data.
Source: NVD, CVSS v3
7.8
CVSS v3
Severity High on the scale from 0 to 10.
Source: pwn.watch, CVE.org
59.8 %
EPSS score
High — model estimates ≥ 50% chance of real-world exploitation within 30 days.
Source: FIRST EPSS, percentile 99.13
Show all metrics
- Severity
- Critical
Priority (0–325)
The priority score is a consolidated metric that condenses several individual signals into a single, action-guiding ranking: technical severity (CVSS), exploitation likelihood (EPSS), known-exploited status (KEV) and the context of the affected asset. The aim is to answer the only truly important question in vulnerability management: what first?
Read in glossary- 247.08 Methodology
Exploit maturity
An exploit is code or a technique that specifically uses a concrete vulnerability to force unintended behaviour — such as executing code or escalating privileges. It is the tool that turns a theoretical flaw into a practical attack.
Read in glossary- actively exploited
XIEM Effective CVSS
XIEM® is the tiered managed-security operating model from NEOSEC and a registered trademark of NEOSEC GmbH. It extends classic SIEM — the central collection, normalisation and correlation of security-relevant events — with endpoint forensics, network visibility and deception technology, and consolidates them into three building tiers: Sentry, Orchestrate and Command.
Read in glossary- 7.8 Methodology
CVSS v3
CVSS is the globally established, open standard for assessing the technical severity of a vulnerability on a scale from 0 to 10. It describes how easily a flaw can be exploited and what damage it can cause — but not how likely its actual exploitation is. CVSS and the complementary EPSS deliberately answer different questions.
Read in glossary- 7.8
EPSS score
The EPSS score is the absolute model output for an individual vulnerability: the estimated probability of real-world exploitation within the next 30 days, expressed as a value between 0 and 1 (i.e. 0 % to 100 %). A score of 0.42 means „the model estimates a 42 % chance of real-world exploitation within 30 days“.
Read in glossary- 59.8 %
- High — model estimates ≥ 50% chance of real-world exploitation within 30 days.
EPSS percentile
The EPSS percentile is the relative position of a vulnerability within all EPSS-scored CVEs, expressed as a value between 0 and 1. A percentile of 0.90 means „this CVE has a higher EPSS score than 90 % of all other scored CVEs“. Unlike the EPSS score, it is not a probability — but a positioning within a ranking.
Read in glossary- 99.13
- Critical — this CVE ranks in the top fifth of all CVEs scored today (rank ≥ 80%).
KEV status
The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching.
Read in glossary- Actively exploited
- Published
In CISA KEV since
The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching.
Read in glossary- CISA assessment (SSVC)
- Exploitation: active · not automatable · Technical impact: total
- Source: CISA Vulnrichment, as of 12 February 2024
CWE
CWE is a catalogue of typical weakness types in software and hardware — such as flawed input validation, unsafe memory handling or poor authentication. Where a CVE names a concrete vulnerability in a concrete product, a CWE describes the underlying class of defect.
Read in glossary- CWE-822
Response and mitigation
Why act now?
Prioritisation rationale
This is a low-complexity local privilege escalation that needs no user interaction and gives full impact on confidentiality, integrity and availability. A functional exploit is publicly documented, exploitation likelihood ranks among the highest of all scored CVEs, and CISA flags known use in ransomware campaigns. Attackers chain it after initial access (phishing, stolen credentials) to turn admin or service-account rights into kernel control and switch off EDR before deploying payloads. The local vector should not lower its priority: virtually every Windows estate is affected and a vendor fix exists. Close it within your emergency patch window, starting with admin, RDS and server tiers.
Runbook step 1
Immediate response (0-24 h)
- Deploy the February 2024 cumulative update (Patch Tuesday, 13 Feb 2024) across all Windows clients and servers. Target builds per context: Windows 10 1809 and Server 2019 at least 10.0.17763.5458, Windows 10 21H2 10.0.19044.4046, Windows 10 22H2 10.0.19045.4046, Windows 11 21H2 10.0.22000.2777, Windows 11 22H2 10.0.22621.3155, Windows 11 23H2 10.0.22631.3155, Server 2022 10.0.20348.2322. Look up the KB number for each build in the Microsoft Security Update Guide entry for CVE-2024-21338.
- Verify compliance by OS build/UBR via MDM/SCCM reporting or
Get-ComputerInfo. Flag anything below target as critical-open. - Patch these first: admin workstations, jump hosts, RDS/terminal servers, VDI pools, and servers with many interactive or service logons. Kernel-level privilege escalation pays off most for an attacker on these systems.
- On any suspect host, confirm EDR/AV telemetry is continuous. This bug grants kernel write primitives that are abused to strip kernel callbacks and blind security tooling. Isolate hosts with telemetry gaps and capture memory before any reboot.
- Inventory local admin accounts and rotate LAPS passwords. Observed exploitation is "admin-to-kernel", starting from already-elevated or service-account context.
Runbook step 2
Mitigation layers
- Configuration: Review the start type of appid.sys and the AppIDSvc service. Where AppLocker and Smart App Control are provably unused, disabling AppIDSvc reduces attack surface. Test the impact on existing AppLocker policy first, and treat this as interim only, not a substitute for patching.
- IAM / least privilege: Remove standing local admin rights from end users (EPM, LAPS). Harden service accounts and deny them interactive logon via GPO.
- Endpoint hardening: Enable HVCI/Memory Integrity, Credential Guard and LSA protection. These will not stop pure data-only (DKOM) kernel tampering, but they raise the cost of follow-on actions such as loading unsigned drivers or dumping credentials.
- EDR configuration: Enforce tamper protection. Create a central heartbeat alert that fires when a sensor stops reporting for more than N minutes.
- Network segmentation: Move unpatched hosts into a restricted VLAN. Block client-to-client SMB 445, RPC 135, WinRM 5985/5986 and RDP 3389 to slow lateral movement after a successful escalation.
Runbook step 3
Detection rules
- Sysmon EID 1 / Security 4688: Processes running as
NT AUTHORITY\LOCAL SERVICEwhose parent is notservices.exeorsvchost.exe. Known exploitation impersonates a LOCAL SERVICE token to gain IOCTL access to \Device\AppID. KQL:DeviceProcessEvents | where AccountName =~ "local service" and InitiatingProcessFileName !in~ ("services.exe","svchost.exe") - Security 4672/4624 + 4688: SeDebugPrivilege or SeImpersonatePrivilege assigned to unusual processes, followed shortly by token duplication. Sigma shape:
EventID 4688 AND TokenElevationType="%%1937" AND ParentImage NOT IN (known admin tooling). - EDR/SIEM health: Kernel/ETW telemetry stops abruptly while the network heartbeat continues. This is a strong rootkit indicator. SPL idea:
| tstats latest(_time) by host | where now()-latest > 900, correlated with firewall logs still showing traffic from the same host. - Sysmon EID 6 / 7045 / 4697: New driver or service installs, plus appid.sys loading on hosts with no AppLocker policy configured. Alert on deviations from baseline.
- Object access: Optionally apply a SACL to \Device\AppID or use EDR handle telemetry to flag handle opens by any process other than AppIDSvc.
- Sysmon EID 1 / Security 4688: Processes running as
Detection rules
No NEOSEC detection rule is available for this vulnerability yet.
Classification under NIS2 and CRA
Rule-based classification from exploitation status and severity. It does not replace a case-by-case assessment.
NIS2
NIS2 is EU Directive (EU) 2022/2555 to raise the level of cybersecurity across the Union. It substantially broadens obligations compared with the first NIS directive: more sectors, mandatory risk management, staged reporting duties and personal accountability of senior management.
Read in glossary- Actively exploited: treat the vulnerability as a priority in vulnerability handling under Art. 21(2)(e) NIS2. If it is exploited in your environment, check the reporting obligation under Art. 23 (early warning within 24 hours).
CRA
The CRA is EU Regulation (EU) 2024/2847 setting horizontal cybersecurity requirements for „products with digital elements“ — from industrial controllers and software to connected consumer devices. For the first time manufacturers must ensure security across the entire product lifecycle, handle vulnerabilities and provide security updates.
Read in glossary- Since 11.09.2026, manufacturers of affected products with digital elements must report actively exploited vulnerabilities under Art. 14 CRA, with an early warning within 24 hours via ENISA's single reporting platform.
ISO/IEC 27001
ISO/IEC 27001 is the internationally leading standard for an information security management system (ISMS). It describes a risk-based, process-oriented framework to systematically plan, implement, review and improve information security.
Read in glossary- Control A.8.8, management of technical vulnerabilities: assess relevance to your systems, plan remediation and keep evidence.
Description
Windows Kernel Elevation of Privilege Vulnerability
Source: pwn.watch, cvelistv5, CISA KEV Catalog, NVD (NIST), CVE.org (MITRE)
Affected products
The following versions are affected. Older releases of the same product line are also vulnerable unless stated otherwise.
| Affected versions | Fixed in | ||
|---|---|---|---|
| Microsoft | Windows 10 Version 1809 |
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| Microsoft | Windows 10 Version 21H2 |
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| Microsoft | Windows 10 Version 22H2 |
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| Microsoft | Windows 11 version 21H2 |
|
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| Microsoft | Windows 11 version 22H2 |
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| Microsoft | Windows 11 version 22H3 |
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| Microsoft | Windows 11 Version 23H2 |
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| Microsoft | Windows Server 2019 |
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| Microsoft | Windows Server 2019 (Server Core installation) |
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| Microsoft | Windows Server 2022 |
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| Microsoft | Windows Server 2022, 23H2 Edition (Server Core installation) |
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Vendors and products
- Microsoft Microsoft Windows 10 1809
- Microsoft Microsoft Windows 10 21H2
- Microsoft Microsoft Windows 10 22h2
- Microsoft Windows 10 Version 1809
- Microsoft Windows 10 Version 21h2
- Microsoft Windows 10 Version 22h2
- Microsoft Windows 11 21h2
- Microsoft Microsoft Windows 11 22H2
- Microsoft Microsoft Windows 11 23H2
- Microsoft Windows 11 Version 21h2
- Microsoft Windows 11 Version 22h2
- Microsoft Windows 11 Version 22h3
Affected operating systems
| Windows | microsoft | windows_10_1809 | — |
| Windows | microsoft | windows_10_21h2 | — |
| Windows | microsoft | windows_10_22h2 | — |
| Windows | microsoft | windows_11_21h2 | — |
| Windows | microsoft | windows_11_22h2 | — |
| Windows | microsoft | windows_11_23h2 | — |
| Windows | microsoft | windows_server_2019 | — |
| Windows | microsoft | windows_server_2022 | — |
| Windows | microsoft | windows_server_2022_23h2 | — |
Weakness classes (CWE)
CWE-822Untrusted Pointer Dereference
Base
The product obtains a value from an untrusted source, converts this value to a pointer, and dereferences the resulting pointer.
Entry at MITRE CWE-822
Public exploit references
Publicly reported proof-of-concepts, exploit modules and detection templates for this vulnerability. NEOSEC links to the original sources only and does not provide any exploit code.
| CISA KEV Catalog | CISA Known Exploited Vulnerability (opens in a new tab)cisa.gov | actively exploited | |
| Packet Storm | Packet Storm 190586 (opens in a new tab)packetstorm.news | PoC (publicly reported)reported, not verified | — |
| Exploit-DB | EDB-ID 52275 (opens in a new tab)exploit-db.com | PoC (publicly reported)reported, not verified | — |
References & sources
- Microsoft Security Update GuideWindows Kernel Elevation of Privilege VulnerabilityVendor advisory, Patch, pwn-watch
- cisa.govknown-exploited-vulnerabilities-catalog?field_cve=CVE-2024-21338government-resource
- exploit-db.comexploits/52275
- packetstorm.newsfiles/id/190586
- decoded.avast.iojanvojtesek/lazarus-and-the-fudmodule-rootkit-beyond-byovd-with…x_transferred
- pwn.watchpwn.watch: Microsoft Windows Kernel Exposed IOCTL with Insufficient Access Controlpwn-watch
- NVD (NIST)NVD: CVE-2024-21338pwn-watch
- cisa.govCISA Known Exploited Vulnerabilities Catalogpwn-watch
Changes to this CVE
Who changed this CVE and when: NVD (analysis, affected products, CVSS), the CVE publisher (CNA) and additional providers such as CISA (ADP).
Record modifiedMicrosoft
1 individual change: Affected versions (publisher)
Show the original change
Individual changes of this event as published by NVD Type Action Before After Affected versions (publisher) changed Windows 10 Version 1809, Windows 10 Version 1809, Windows Server 2019 (+9)Windows 10 Version 1809, Windows 10 Version 1809, Windows 10 Version 21H2 (+9)Source identifier: secure@microsoft.com
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<a href="https://intel.neosec.eu/en/cve/CVE-2024-21338"><img src="https://intel.neosec.eu/badge/cve/CVE-2024-21338.svg?lang=en" alt="CVE-2024-21338 – NEOSEC Intel" height="20"></a>