CVE tracker / CVE-2026-21239

CVE-2026-21239

CVE-2026-21239 is the Windows Kernel Elevation of Privilege Vulnerability. Microsoft rates it Important, CVSS 7.8. It is not in CISA's Known Exploited Vulnerabilities catalog. Published February 10, 2026.

Risk summary

HighElevation of Privilege
7.8
CVSS v3 base
0.4%
EPSS: chance of exploitation in 30 days
High
Severity
Important
Microsoft's rating
Less Likely
Microsoft: exploitation
No
In CISA KEV

Microsoft describes it: “Heap-based buffer overflow in Windows Kernel allows an authorized attacker to elevate privileges locally.”

How to fix it

Microsoft lists 29 affected products and the update that fixes each:

What Microsoft changed

Details

Weakness
CWE-122: Heap-based Buffer Overflow
Publicly disclosed (Microsoft)
No
Exploited (Microsoft)
No
Known exploited (CISA KEV)
Not listed
Published
February 10, 2026
Last revised
February 10, 2026

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References

Microsoft Security Update Guide NVD CVE record CWE

From Microsoft, CISA, NVD and FIRST data; the Microsoft details were read when this page was opened. Check the references above before you act.