CVE-2026-50359: Microsoft XML Core Services use after free privilege escalation

CVE-2026-50359 · Severity: high · CVSS 7 · Published 2026-07-14

A security vulnerability exists in Microsoft XML Core Services, a component used by Windows to process XML data. An attacker who already has basic access to a computer could exploit this flaw to gain higher-level administrative privileges. This could allow them to take full control of the affected system, potentially leading to data theft or the installation of malicious software.

Technologies: Microsoft Windows 10 Version 1607, Microsoft Windows 10 Version 1809, Microsoft Windows 10 Version 21H2, Microsoft Windows 10 Version 22H2, Microsoft Windows 11 Version 24H2, Microsoft Windows 11 Version 25H2, Microsoft Windows 11 Version 26H1, Microsoft Windows Server 2012, Microsoft XML Core Services. Vendors: Microsoft.

Quick answers

Is CVE-2026-50359 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-50359 being exploited in the wild.
How severe is CVE-2026-50359?
High severity, with a CVSS score of 7, published 14 July 2026.
Which products and versions are affected?
Microsoft Windows 10 Version 1607 10.0.14393.0 to 10.0.14393.9339; Microsoft Windows 10 Version 1809 10.0.17763.0 to 10.0.17763.9020; Microsoft Windows 10 Version 21H2 10.0.19044.0 to 10.0.19044.7548; Microsoft Windows 10 Version 22H2 10.0.19045.0 to 10.0.19045.7548; and 4 more.
Is there a fix for CVE-2026-50359?
No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
How is CVE-2026-50359 attacked?
It is attacked with local access, in an operating system.
Am I affected by CVE-2026-50359?
Check whether you run Microsoft Windows 10 Version 1607, Microsoft Windows 10 Version 1809, Microsoft Windows 10 Version 21H2 or one of the others listed at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

A use-after-free vulnerability (CWE-416) exists in Microsoft XML Core Services (MSXML). The flaw is triggered when the system improperly handles objects in memory, allowing an attacker to reuse a memory pointer after it has been freed. To exploit this, an attacker must first have local access to the system with low-level user privileges. Successful exploitation allows the attacker to elevate their privileges to a higher level, potentially gaining full system control. The attack complexity is rated as high, suggesting specific timing or environmental conditions are required for a successful exploit.

Affected products

  • Microsoft Windows 10 Version 1607 10.0.14393.0 to 10.0.14393.9339
  • Microsoft Windows 10 Version 1809 10.0.17763.0 to 10.0.17763.9020
  • Microsoft Windows 10 Version 21H2 10.0.19044.0 to 10.0.19044.7548
  • Microsoft Windows 10 Version 22H2 10.0.19045.0 to 10.0.19045.7548
  • 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 2012 6.2.9200.0 to 6.2.9200.26226
  • Microsoft Microsoft XML Core Services (MSXML)

Timeline

  • 2026-07-14: disclosed
  • 2026-07-14: advisory

References

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