Junglewise Threat Intelligence

CVE-2026-50403: Microsoft Windows Runtime privilege escalation via race condition

CVE-2026-50403 · Severity: high · CVSS 7 · Published 2026-07-14

Technologies: Microsoft Windows 11 Version 26H1, Microsoft Windows 11 Version 24H2, Microsoft Windows Server 2025, Microsoft Windows 11, Microsoft Windows 11 Version 25H2. Vendors: Microsoft.

Executive brief

A security vulnerability exists in the Windows Runtime, a core component of the Windows operating system used by applications to interact with the system. An attacker who already has basic access to a computer could exploit this flaw to gain higher-level administrative permissions. This could allow them to bypass security restrictions, access sensitive data, or install malicious software.

Technical details

This vulnerability is a race condition (CWE-362) in the Windows Runtime (WinRT) that can lead to a use-after-free (CWE-416) scenario. An authorized attacker with low-level local privileges can exploit improper synchronization of shared resources during concurrent execution. Successful exploitation allows the attacker to elevate their privileges to a higher level, potentially gaining full system control. The attack requires the attacker to win a timing race, making the complexity high, but it does not require user interaction. Microsoft has released security updates to address this issue across affected versions of Windows 11 and Windows Server 2025.

Affected products

  • Microsoft Windows 11 Version 24H2 10.0.26100.0 to 10.0.26100.8875
  • Microsoft Windows 11 Version 25H2 10.0.26200.0 to 10.0.26200.8875
  • Microsoft Windows 11 version 26H1 10.0.28000.0 to 10.0.28000.2269
  • Microsoft Windows Server 2025 10.0.26100.0 to 10.0.26100.33158

Timeline

  • 2026-07-14: disclosed: Initial publication by Microsoft and NVD.
  • 2026-07-14: patched: Security updates made available by Microsoft.

References

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