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Δ / VULNERABILITY RECORD

CVE-2026-21251.

Source-reported disclosure and enrichment record.

SEVERITY / CVSSHIGH / 7.8No severity score in this snapshot.
EXPLOITATION STATUSNot listed in the cached KEV catalogThis does not establish absence of exploitation.
RECORD STATUSMicrosoft vendor recordModified Feb 10, 2026

Disclosure summary

Use after free in Windows Cluster Client Failover allows an authorized attacker to elevate privileges locally.

Source-reported weakness categories

CWE-416

Source-specific records & product guidance

Sources retain their own attribution and scoring. Follow the original record to confirm affected versions, fixed releases, and configuration conditions.

Microsoft Security Updates (CVRF) · 2026-Feb

Open original source · Updated Feb 10, 2026

Cluster Client Failover (CCF) Elevation of Privilege Vulnerability

Maximum of vendor-reported product scores; products and fixed builds are associations, not a universal affected-version statement.

Microsoft maximum product score: 7.8

VendorProduct / associationVersion / bounds
Microsoft update guideWindows Server 2019 (MSRC status code 3)
Microsoft update guideWindows Server 2019 (Server Core installation) (MSRC status code 3)
Microsoft update guideWindows Server 2022 (MSRC status code 3)
Microsoft update guideWindows Server 2022 (Server Core installation) (MSRC status code 3)
Microsoft update guideWindows Server 2025 (Server Core installation) (MSRC status code 3)
Microsoft update guideWindows Server 2022, 23H2 Edition (Server Core installation) (MSRC status code 3)
Microsoft update guideWindows Server 2025 (MSRC status code 3)
Microsoft update guideWindows Server 2016 (MSRC status code 3)
Microsoft update guideWindows Server 2016 (Server Core installation) (MSRC status code 3)

Vendor remediation references

Original records & references

PUBLISHED 2026-02-10T03:00:00-05:00
MODIFIED 2026-02-10T03:00:00-05:00
INGESTED 2026-10-08T12:45:18-04:00