Exploited vulnerability · CISA KEV

Is CVE-2024-21338 exploited? Yes: in CISA KEV since 4 Mar 2024

Gociux · Microsoft Windows · data: CISA KEV, CVE record, FIRST EPSS

Yes. CVE-2024-21338, Microsoft Windows Kernel Exposed IOCTL with Insufficient Access Control Vulnerability, is being exploited in the wild. CISA added it to its Known Exploited Vulnerabilities catalog on 4 Mar 2024, 20 days after it was published. It is known to be used in ransomware campaigns. It affects Microsoft Windows. If you run it, CISA's required action is: Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.

What it is

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.

What to do

1. Check whether you run it. Look for Windows in your asset inventory, including appliances and cloud images. Stack check lists every exploited Microsoft CVE at once.
2. Apply the fix. Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.
3. If you can't patch today, take the affected service off the internet or restrict who can reach it, and check its logs for signs of compromise since 13 Feb 2024.
4. Get told next time. Email alerts when CISA adds a CVE for Microsoft.

Other exploited CVEs in Windows

• CVE-2026-96951: Microsoft Windows Command Injection Vulnerability (13 Oct 2026)
• CVE-2026-81963: Microsoft Windows Link Following Vulnerability (8 Sep 2026)
• CVE-2026-85880: Microsoft Windows Heap-Based Buffer Overflow Vulnerability (8 Sep 2026)
• CVE-2008-4250: Microsoft Windows Buffer Overflow Vulnerability (20 May 2026)
• CVE-2026-32202: Microsoft Windows Protection Mechanism Failure Vulnerability (28 Apr 2026)
• CVE-2025-60710: Microsoft Windows Link Following Vulnerability (13 Apr 2026)

References

• msrc.microsoft.com/update-guide/vulnerability/CVE-2024-21338
• nvd.nist.gov/vuln/detail/CVE-2024-21338

Sources: CISA KEV (exploitation, ransomware use, required action, due date), the CVE record (publication date, CVSS, CNA), NVD and FIRST EPSS (live score). More: all KEV additions in March 2024 · Microsoft scorecard · act-now radar.