CVE-2026-34332
High CVSS 8Published 2026-05-12 ยท last changed 2026-06-17
The fix
Microsoft fixes this in updatesKB5087539, KB5087423. The fixed build differs per Windows version, so the row that matters is the one matching the machine you are looking at.
| Windows version | Fixed in build | Update | Released |
|---|---|---|---|
| Windows Server 2025 | 10.0.26100.32860 | KB5087539, KB5087423 | 2026-09-18 |
| Windows Server 2025 (Server Core installation) | 10.0.26100.32860 | KB5087539, KB5087423 | 2026-09-18 |
Having the KB is not the same as knowing whether a machine has it. Windows updates supersede each other, so the update you installed often covers a fix that shipped in an earlier one. Paste your build into the patch checker and it walks that chain for you.
What it is
Use after free in Windows Kernel-Mode Drivers allows an authorized attacker to execute code over a network.
Sources
CVSS vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:H