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Windows 10 1809Operating system · Microsoft

CVE-2026-42828

HIGH · 7.8 CVSS v3.1 Published 2026-06-09
Fix available
A fix is available. Upgrade to 10.0.17763.8880 / 10.0.19044.7417 or later.
See remediation →
80/100
Remediation priority · High
Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
Buffer over-read in Windows Projected File System Filter Driver allows an authorized attacker to elevate privileges locally.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · moderate confidence

A buffer over-read vulnerability exists in the Windows Projected File System Filter Driver (projfs.sys), a kernel-mode component. The flaw allows a locally authorized attacker to read beyond buffer boundaries and escalate privileges to higher integrity levels, potentially achieving SYSTEM privileges.

MitigationApply the relevant Microsoft security update for this CVE through Windows Update or enterprise patch management systems. Verify the patched driver version matches the vendor-recommended version.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Windows 10 1809Operating system
Affected:< 10.0.17763.8880
Windows 10 21h2Operating system
Affected:< 10.0.19044.7417
Windows 10 22h2Operating system
Affected:< 10.0.19045.7417
Windows 11 23h2Operating system
Affected:< 10.0.22631.7219
Windows 11 24h2Operating system
Affected:< 10.0.26100.8655
Windows 11 25h2Operating system
Affected:< 10.0.26200.8655
Windows 11 26h1Operating system
Affected:< 10.0.28000.2269
Windows Server 2019Operating system
Affected:< 10.0.17763.8880

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Local
Complexity
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Check Windows version against affected ranges
    Run 'winver' or 'systeminfo | findstr /B /C:"OS Name" /C:"OS Version"' to obtain the installed Windows build number. Compare the build (e.g., 17763, 19044, 19045, 22631, 26100, 26200, 28000) to the affected version thresholds: 17763.8880, 19044.7417, 19045.7417, 22631.7219, 26100.8655, 26200.8655, 28000.2269.
    Affected if The installed build number is lower than the corresponding threshold for your Windows version.
  2. Verify if Projected File System (ProjFS) feature is enabled
    Check the Windows optional features list by running 'dism /Online /Get-Features' or checking the registry key 'HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Setup\State' for ImageState VALUE "IMAGE_STATE_COMPLETE", then 'Get-WindowsOptionalFeature -Online' in PowerShell to see if 'ClientForProjectedFS' or 'ProjectedFS' is enabled.
    Affected if The ProjFS feature (ClientForProjectedFS or ProjectedFS) is enabled on the system.
  3. Check ProjFS filter driver version
    Locate the ProjFS driver file (projfs.sys typically in C:\Windows\System32\drivers\) and right-click properties to view File Version, or run 'dir C:\Windows\System32\drivers\projfs.sys' to see the file. Alternatively, use 'driverquery /v | findstr projfs' if the driver is loaded.
    Affected if The driver file exists and its version is not yet patched to the fixed build versions listed in the affected products.
  4. Confirm driver is loaded in memory
    Run 'sc query projfs' or 'sc query type= driver' and filter for ProjFS-related entries, or use 'fltmc filters' to list loaded file system mini-filters and look for entries containing 'ProjFS' or 'ProjectedFS'.
    Affected if The ProjFS mini-filter driver is actively loaded in kernel memory.

A system is affected if it runs a Windows version with a build number below the specified thresholds AND has the Projected File System (ProjFS) feature or driver enabled/loaded.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 10.0.17763.8880 / 10.0.19044.7417 / 10.0.19045.7417 or later
Fixed in 10.0.17763.888010.0.19044.741710.0.19045.7417
Interim mitigation

Apply the relevant Microsoft security update for this CVE through Windows Update or enterprise patch management systems. Verify the patched driver version matches the vendor-recommended version.

Recommended fix High confidence

Windows 10 1809: Build 10.0.17763.8880 | Windows 10 21h2: Build 10.0.19044.7417 | Windows 10 22h2: Build 10.0.19045.7417 | Windows 11 23h2: Build 10.0.22631.7219 | Windows 11 24h2: Build 10.0.26100.8655 | Windows 11 25h2: Build 10.0.26200.8655 | Windows 11 26h1: Build 10.0.28000.2269 | Windows Serve

  1. Open Windows Settings and navigate to Windows Update
  2. Check for updates and install all available security updates
  3. Restart the system if prompted to complete the installation
  4. Verify the installed build number matches or exceeds the fixed version for your Windows edition
Caveat Standard Windows update - no breaking changes expected for this security patch

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Windows 10 1809 Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing3.0 h
  • Review / QA2.0 h
11.0 hours of engineering $1,930
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Scan for this in your stack

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-42828 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data