CVE-2025-21326
High CVSS 7.8Published 2025-01-14 ยท last changed 2026-06-17
The fix
Microsoft fixes this in updatesKB5049984, KB5050009. 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 2022, 23H2 Edition (Server Core installation) | 10.0.25398.1369 | KB5049984 | 2026-09-17 |
| Windows Server 2025 | 10.0.26100.2894 | KB5050009 | 2026-09-17 |
| Windows Server 2025 (Server Core installation) | 10.0.26100.2894 | KB5050009 | 2026-09-17 |
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
Internet Explorer Remote Code Execution Vulnerability
Sources
CVSS vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H