CVE-2026-20817 Windows Error Reporting Service Elevation of Privilege Vulnerability
An authorized local attacker can elevate privileges via improper permission handling in the Windows Error Reporting Service.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-20817?
CVE-2026-20817 is a high-severity vulnerability in Microsoft Windows 10 21h2, published on 13 Jan 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
Improper handling of insufficient permissions or privileges in Windows Error Reporting allows an authorized attacker to elevate privileges locally.
Weakness: CWE-280
Which versions are affected by CVE-2026-20817?
It affects 8 products.
Products include Microsoft Windows 10 21h2, Microsoft Windows 10 22h2, Microsoft Windows 11 23h2, Microsoft Windows 11 24h2, Microsoft Windows 11 25h2, Microsoft Windows Server 2022 and 2 more.
How do I fix CVE-2026-20817?
No fix has been published for CVE-2026-20817 yet. Limit exposure of the affected software until one is available.
Is CVE-2026-20817 being exploited?
There is no known exploitation of CVE-2026-20817 in the wild and no public exploit code.
Public exploit code: 3 proofs of concept on GitHub.
Other vulnerabilities in Microsoft Windows 10 21h2
- CVE-2025-21333 Microsoft Windows Hyper-V NT Kernel Integration VSP Heap-based Buffer Overflow
- CVE-2025-21334 Microsoft Windows Hyper-V NT Kernel Integration VSP Use-After-Free
- CVE-2025-21335 Microsoft Windows Hyper-V NT Kernel Integration VSP Use-After-Free
- CVE-2026-42904 Windows TCP/IP Elevation of Privilege Vulnerability
- CVE-2026-105733 Windows Hyper-V Remote Code Execution Vulnerability
Sources
Also known as GHSA-p4qh-cj7j-r785.