CVE tracker / CVE-2026-113771

CVE-2026-113771

CVE-2026-113771 is the Windows Container Isolation FS Filter Driver (unionfs.sys) Elevation of Privilege Vulnerability. Microsoft rates it Important, CVSS 5.5. It is not in CISA's Known Exploited Vulnerabilities catalog. Published November 10, 2026.

Risk summary

MediumElevation of Privilege

5.5

CVSS v3 base

Medium

Severity

Important

Microsoft's rating

Less Likely

Microsoft: exploitation

In CISA KEV

Microsoft describes it: “Off-by-one error in Windows Container Isolation FS Filter Driver (unionfs.sys) allows an authorized attacker to elevate privileges locally.”

How to fix it

Microsoft lists 2 affected products and the update that fixes each:

KB5132059 · fixed build 10.0.28000.3501
Windows 11 version 26H1 for x64-based Systems, Windows 11 Version 26H1 for ARM64-based Systems

What Microsoft changed

November 10, 2026: Information published.

Details

Weakness: CWE-193: Off-by-one Error
Publicly disclosed (Microsoft): No
Exploited (Microsoft): No
Known exploited (CISA KEV): Not listed
Published: November 10, 2026
Last revised: November 10, 2026

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References

Microsoft Security Update Guide NVD CVE record CWE

From Microsoft, CISA, NVD and FIRST data; the Microsoft details were read when this page was opened. Check the references above before you act.