What’s Vulnerable › Vulnerabilities

CVE-2026-50428: Windows Container Isolation FS Filter Driver (unionfs.sys) Information Disclosure Vulnerability

• Severity: medium (CVSS 5.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.4% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-07-14 · updated 2026-10-28
• Weakness: CWE-125

Description

Out-of-bounds read in Windows Container Isolation FS Filter Driver (unionfs.sys) allows an authorized attacker to disclose information locally.

Affected products

• Microsoft Windows 11 version 26H1: before 10.0.28000.2269; before 10.0.28000.2525 — fixed in 10.0.28000.2269, 10.0.28000.2525
• Microsoft Windows 11 version 26H1: from 10.0.28000.0 before 10.0.28000.2525 — fixed in 10.0.28000.2525

How to fix

Upgrade to a fixed version: Microsoft Windows 11 version 26H1 10.0.28000.2269, 10.0.28000.2525; Microsoft Windows 11 version 26H1 10.0.28000.2525. Check the vendor advisory for mitigations.

References

• https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-50428

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