CVE-2026-83903
High CVSS 7.8Published 2026-10-13 ยท last changed 2026-10-13
The fix
Microsoft fixes this in updatesKB5127648, KB5126646. 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 11 Version 24H2 for ARM64-based Systems | 10.0.26100.9711 | KB5127648 | 2026-10-13 |
| Windows 11 Version 24H2 for x64-based Systems | 10.0.26100.9711 | KB5127648 | 2026-10-13 |
| Windows 11 Version 25H2 for ARM64-based Systems | 10.0.26200.9711 | KB5127648 | 2026-10-13 |
| Windows 11 Version 25H2 for x64-based Systems | 10.0.26200.9711 | KB5127648 | 2026-10-13 |
| Windows 11 Version 26H2 for ARM64-based Systems | 10.0.26300.9711 | KB5127648 | 2026-10-13 |
| Windows 11 Version 26H2 for x64-based Systems | 10.0.26300.9711 | KB5127648 | 2026-10-13 |
| Windows Server 2025 | 10.0.26100.33650 | KB5126646 | 2026-10-13 |
| Windows Server 2025 (Server Core installation) | 10.0.26100.33650 | KB5126646 | 2026-10-13 |
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
Heap-based buffer overflow in Windows Direct Composition allows an authorized attacker to elevate privileges locally.
Sources
CVSS vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H