# CVE-2026-34331: Win32k Elevation of Privilege Vulnerability CVE-2026-34331 is fixed in 31 products on 1 platform, first by KB5087537, released May 12, 2026. It is not reported as exploited. Patch Radar priority: High. - Web page: https://patchblox.com/security/cve/CVE-2026-34331 - Priority: High - CVSS: 7.0 (Important) - EPSS: 0.0019 - CISA KEV: not listed - Exploited (vendor report): no - Publicly disclosed: no - Vendor exploitability assessment: Exploitation Unlikely - Published: May 12, 2026 - Weakness: Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition') - Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-34331 ## Description

Concurrent execution using shared resource with improper synchronization ('race condition') in Windows Win32K - GRFX allows an authorized attacker to elevate privileges locally.

## Where it's fixed | Platform | Product | Fixed in | Fix | Released | |---|---|---|---|---| | Microsoft | Windows 10 Version 1607 for 32-bit Systems | 14393.9140 | [KB5087537](https://patchblox.com/security/data/fix/microsoft/kb5087537.md) | May 12, 2026 | | Microsoft | Windows 10 Version 1607 for x64-based Systems | 14393.9140 | [KB5087537](https://patchblox.com/security/data/fix/microsoft/kb5087537.md) | May 12, 2026 | | Microsoft | Windows 10 Version 1809 for 32-bit Systems | 17763.8755 | [KB5087538](https://patchblox.com/security/data/fix/microsoft/kb5087538.md) | May 12, 2026 | | Microsoft | Windows 10 Version 1809 for x64-based Systems | 17763.8755 | [KB5087538](https://patchblox.com/security/data/fix/microsoft/kb5087538.md) | May 12, 2026 | | Microsoft | Windows 10 Version 21H2 for 32-bit Systems | | [KB5087544](https://patchblox.com/security/data/fix/microsoft/kb5087544.md) | May 12, 2026 | | Microsoft | Windows 10 Version 21H2 for ARM64-based Systems | | [KB5087544](https://patchblox.com/security/data/fix/microsoft/kb5087544.md) | May 12, 2026 | | Microsoft | Windows 10 Version 21H2 for x64-based Systems | | [KB5087544](https://patchblox.com/security/data/fix/microsoft/kb5087544.md) | May 12, 2026 | | Microsoft | Windows 10 Version 22H2 for 32-bit Systems | | [KB5094127](https://patchblox.com/security/data/fix/microsoft/kb5094127.md) | Jun 9, 2026 | | Microsoft | Windows 10 Version 22H2 for ARM64-based Systems | | [KB5094127](https://patchblox.com/security/data/fix/microsoft/kb5094127.md) | Jun 9, 2026 | | Microsoft | Windows 10 Version 22H2 for x64-based Systems | | [KB5094127](https://patchblox.com/security/data/fix/microsoft/kb5094127.md) | Jun 9, 2026 | | Microsoft | Windows 11 Version 23H2 for ARM64-based Systems | 22631.7079 | [KB5087420](https://patchblox.com/security/data/fix/microsoft/kb5087420.md) | May 12, 2026 | | Microsoft | Windows 11 Version 23H2 for x64-based Systems | 22631.7219 | [KB5093998](https://patchblox.com/security/data/fix/microsoft/kb5093998.md) | Jun 9, 2026 | | Microsoft | Windows 11 Version 24H2 for ARM64-based Systems | | [KB5089549](https://patchblox.com/security/data/fix/microsoft/kb5089549.md) | May 12, 2026 | | Microsoft | Windows 11 Version 24H2 for ARM64-based Systems | | [KB5089466](https://patchblox.com/security/data/fix/microsoft/kb5089466.md) | May 12, 2026 | | Microsoft | Windows 11 Version 24H2 for x64-based Systems | | [KB5089549](https://patchblox.com/security/data/fix/microsoft/kb5089549.md) | May 12, 2026 | | Microsoft | Windows 11 Version 24H2 for x64-based Systems | | [KB5089466](https://patchblox.com/security/data/fix/microsoft/kb5089466.md) | May 12, 2026 | | Microsoft | Windows 11 Version 25H2 for ARM64-based Systems | | [KB5089549](https://patchblox.com/security/data/fix/microsoft/kb5089549.md) | May 12, 2026 | | Microsoft | Windows 11 Version 25H2 for ARM64-based Systems | | [KB5089466](https://patchblox.com/security/data/fix/microsoft/kb5089466.md) | May 12, 2026 | | Microsoft | Windows 11 Version 25H2 for x64-based Systems | | [KB5089549](https://patchblox.com/security/data/fix/microsoft/kb5089549.md) | May 12, 2026 | | Microsoft | Windows 11 Version 25H2 for x64-based Systems | | [KB5089466](https://patchblox.com/security/data/fix/microsoft/kb5089466.md) | May 12, 2026 | | Microsoft | Windows 11 Version 26H1 for ARM64-based Systems | 28000.2113 | [KB5089548](https://patchblox.com/security/data/fix/microsoft/kb5089548.md) | May 12, 2026 | | Microsoft | Windows 11 version 26H1 for x64-based Systems | 28000.2113 | [KB5089548](https://patchblox.com/security/data/fix/microsoft/kb5089548.md) | May 12, 2026 | | Microsoft | Windows Server 2012 | | [KB5087470](https://patchblox.com/security/data/fix/microsoft/kb5087470.md) | May 12, 2026 | | Microsoft | Windows Server 2012 (Server Core installation) | | [KB5087470](https://patchblox.com/security/data/fix/microsoft/kb5087470.md) | May 12, 2026 | | Microsoft | Windows Server 2012 R2 | | [KB5087471](https://patchblox.com/security/data/fix/microsoft/kb5087471.md) | May 12, 2026 | | Microsoft | Windows Server 2012 R2 (Server Core installation) | | [KB5087471](https://patchblox.com/security/data/fix/microsoft/kb5087471.md) | May 12, 2026 | | Microsoft | Windows Server 2016 | 14393.9140 | [KB5087537](https://patchblox.com/security/data/fix/microsoft/kb5087537.md) | May 12, 2026 | | Microsoft | Windows Server 2016 (Server Core installation) | 14393.9140 | [KB5087537](https://patchblox.com/security/data/fix/microsoft/kb5087537.md) | May 12, 2026 | | Microsoft | Windows Server 2019 | 17763.8755 | [KB5087538](https://patchblox.com/security/data/fix/microsoft/kb5087538.md) | May 12, 2026 | | Microsoft | Windows Server 2019 (Server Core installation) | 17763.8755 | [KB5087538](https://patchblox.com/security/data/fix/microsoft/kb5087538.md) | May 12, 2026 | | Microsoft | Windows Server 2022 | 20348.5074 | [KB5087424](https://patchblox.com/security/data/fix/microsoft/kb5087424.md) | May 12, 2026 | | Microsoft | Windows Server 2022 | 20348.5139 | [KB5087545](https://patchblox.com/security/data/fix/microsoft/kb5087545.md) | May 12, 2026 | | Microsoft | Windows Server 2022 (Server Core installation) | 20348.5074 | [KB5087424](https://patchblox.com/security/data/fix/microsoft/kb5087424.md) | May 12, 2026 | | Microsoft | Windows Server 2022 (Server Core installation) | 20348.5139 | [KB5087545](https://patchblox.com/security/data/fix/microsoft/kb5087545.md) | May 12, 2026 | | Microsoft | Windows Server 2022, 23H2 Edition (Server Core installation) | 25398.2330 | [KB5087541](https://patchblox.com/security/data/fix/microsoft/kb5087541.md) | May 12, 2026 | | Microsoft | Windows Server 2025 | 26100.32860 | [KB5087539](https://patchblox.com/security/data/fix/microsoft/kb5087539.md) | May 12, 2026 | | Microsoft | Windows Server 2025 | 26100.32772 | [KB5087423](https://patchblox.com/security/data/fix/microsoft/kb5087423.md) | May 12, 2026 | | Microsoft | Windows Server 2025 (Server Core installation) | 26100.32860 | [KB5087539](https://patchblox.com/security/data/fix/microsoft/kb5087539.md) | May 12, 2026 | | Microsoft | Windows Server 2025 (Server Core installation) | 26100.32772 | [KB5087423](https://patchblox.com/security/data/fix/microsoft/kb5087423.md) | May 12, 2026 | --- Data as of 2026-11-07T18:46:35Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo Free to use with attribution: show "Data: Patchblox Patch Radar" with a link to https://patchblox.com/security/patch-radar. Terms, including what needs a written agreement: https://patchblox.com/security/patch-radar/use-the-data Product names, logos and trademarks shown on Patch Radar belong to their respective owners. They are used only to identify the software each security fix applies to and to help readers find their platform. Their use does not imply any affiliation with, or endorsement by, those owners, and Patchblox is not affiliated with any of them.