VulnTideExploited vulnerabilities, by vendor. Data as of 28 Oct 2026.
Known exploitedIn CISA's KEV catalog since 4 March 2024Ransomware use: known
Microsoft Windows

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

Is it exploited?

Yes. CISA added it to the Known Exploited Vulnerabilities catalog on 4 Mar 2024, 20 days after the CVE record was published.

How likely is exploitation in the next 30 days?
59.8%

EPSS score, percentile 99.1 of all scored records

How severe?
7.8 High

CVSS v3.1 base score, given by the CNA

What should I do?

Required action (CISA), due 25 Mar 2024: Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.

Advisories and patches (1)

Which versions are affected?

Affected: 10.0.17763.0 up to, not including, 10.0.17763.5458; 10.0.0 up to, not including, 10.0.17763.5458; 10.0.19043.0 up to, not including, 10.0.19044.4046; 10.0.19045.0 up to, not including, 10.0.19045.4046; 10.0.0 up to, not including, 10.0.22000.2777; 10.0.22621.0 up to, not including, 10.0.22621.3155; 10.0.22631.0 up to, not including, 10.0.22631.3155; 10.0.22631.0 up to, not including, 10.0.22631.3155; 10.0.17763.0 up to, not including, 10.0.17763.5458; 10.0.17763.0 up to, not including, 10.0.17763.5458; 10.0.20348.0 up to, not including, 10.0.20348.2322; 10.0.25398.0 up to, not including, 10.0.25398.709

Versions by product

Source: CISA Known Exploited Vulnerabilities (KEV) catalog, 2026.10.28, as of 28 Oct 2026; FIRST Exploit Prediction Scoring System (EPSS), v2026.06.15, as of 28 Oct 2026; CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.

What to do

Required action, set by CISA

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

CISA due date for this action: 25 March 2024.

Advisories and patches

Linked from CISA's catalog entry

Affected products and versions

As listed in the CVE record.

Microsoft Windows 10 Version 1809
StatusVersions
Affected10.0.17763.0 up to, not including, 10.0.17763.5458
Microsoft Windows 10 Version 1809
StatusVersions
Affected10.0.0 up to, not including, 10.0.17763.5458
Microsoft Windows 10 Version 21H2
StatusVersions
Affected10.0.19043.0 up to, not including, 10.0.19044.4046
Microsoft Windows 10 Version 22H2
StatusVersions
Affected10.0.19045.0 up to, not including, 10.0.19045.4046
Microsoft Windows 11 version 21H2
StatusVersions
Affected10.0.0 up to, not including, 10.0.22000.2777
Microsoft Windows 11 version 22H2
StatusVersions
Affected10.0.22621.0 up to, not including, 10.0.22621.3155
Microsoft Windows 11 version 22H3
StatusVersions
Affected10.0.22631.0 up to, not including, 10.0.22631.3155
Microsoft Windows 11 Version 23H2
StatusVersions
Affected10.0.22631.0 up to, not including, 10.0.22631.3155
Microsoft Windows Server 2019
StatusVersions
Affected10.0.17763.0 up to, not including, 10.0.17763.5458
Microsoft Windows Server 2019 (Server Core installation)
StatusVersions
Affected10.0.17763.0 up to, not including, 10.0.17763.5458
Microsoft Windows Server 2022
StatusVersions
Affected10.0.20348.0 up to, not including, 10.0.20348.2322
Microsoft Windows Server 2022, 23H2 Edition (Server Core installation)
StatusVersions
Affected10.0.25398.0 up to, not including, 10.0.25398.709

Source: CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.

About this vulnerability

Microsoft Windows Kernel contains an exposed IOCTL with insufficient access control vulnerability within the IOCTL (input and output control) dispatcher in appid.sys that allows a local attacker to achieve privilege escalation.

Summary: CISA's KEV catalog, as of 28 Oct 2026.

  • CISA added CVE-2024-21338 to its Known Exploited Vulnerabilities (KEV) catalog on 4 Mar 2024.
  • CISA marks it as known to be used in ransomware campaigns.
  • The due date CISA sets for the required action is 25 Mar 2024.
  • The CVE record was published on 13 Feb 2024, 20 days before it was added to KEV.
  • The CVE record carries a CVSS v3.1 base score of 7.8 (High), given by its CNA.
  • FIRST's EPSS model puts the probability of exploitation in the next 30 days at 59.8% (percentile 99.1), as of 28 Oct 2026.
  • CISA's SSVC assessment in the CVE record: exploitation active, automatable no, technical impact total.

Source: CISA Known Exploited Vulnerabilities (KEV) catalog, 2026.10.28, as of 28 Oct 2026; CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026; FIRST Exploit Prediction Scoring System (EPSS), v2026.06.15, as of 28 Oct 2026. About the data.

Description

Windows Kernel Elevation of Privilege Vulnerability

Windows Kernel Elevation of Privilege Vulnerability

Source: CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.

Weakness

  • CWE-822: Untrusted Pointer Dereference

CWE and CAPEC are maintained by MITRE; the entries are those named in the CVE record and the KEV entry.

Timeline

DateEvent
13 Feb 2024CVE record published
4 Mar 2024Added to CISA KEV
25 Mar 2024CISA due date for the required action
10 Aug 2026CVE record last updated

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