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Actively exploited in the wild. This CVE is on the CISA Known Exploited Vulnerabilities list — treat remediation as urgent. Federal remediation due by 5 Apr 2022. Known ransomware use
Windows 10 1607Operating system · Microsoft

CVE-2019-1064

HIGH · 7.8 CVSS v3.1 Published 2019-06-12
Patch available
A vendor patch is available. No clean upgrade release — apply the published patch.
See remediation →
96/100
Remediation priority · Urgent
In the wild Ransomware Zero-click Patch available

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
An elevation of privilege vulnerability exists when Windows AppX Deployment Service (AppXSVC) improperly handles hard links. An attacker who successfully exploited this vulnerability could run processes in an elevated context. An attacker could then install programs; view, change or delete data. To exploit this vulnerability, an attacker would first have to log on to the system. An attacker could then run a specially crafted application that could exploit the vulnerability and take control of an affected system. The security update addresses the vulnerability by correcting how Windows AppX Deployment Service handles hard links.

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 · high confidence

This is a local privilege escalation vulnerability in Windows AppX Deployment Service (AppXSVC) where improper handling of hard links allows a standard user to elevate to an elevated (SYSTEM) context, enabling arbitrary program installation and data manipulation.

MitigationApply the Microsoft security update (KB4493440 for Windows 10, or respective monthly rollup) that corrects how AppXSVC handles hard links.

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 1607Operating system
Affected:all versions
Windows 10 1703Operating system
Affected:all versions
Windows 10 1709Operating system
Affected:all versions
Windows 10 1803Operating system
Affected:all versions
Windows 10 1809Operating system
Affected:all versions
Windows 10 1903Operating system
Affected:all versions
Windows Server 1709Operating system
Affected:all versions
Windows Server 1803Operating system
Affected:all versions

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. Identify Windows version
    Run 'winver' or check System Properties, or use 'systeminfo | findstr /B /C:"OS Name" /C:"OS Version"' to see the installed Windows version
    Affected if Version is Windows 10 1607, 1703, 1709, 1803, 1809, or 1903; or Windows Server 1709 or 1803
  2. Check if security update is installed
    Run 'wmic qfe list' or 'Get-HotFix | Where-Object {$_.HotFixID -eq "KB4493440"}' in PowerShell to enumerate installed patches
    Affected if KB4493440 or the respective monthly rollup for the affected version is NOT present in the installed updates list
  3. Verify AppXSVC service status
    Run 'sc query AppXSVC' to query the Windows AppX Deployment Service
    Affected if Service exists and is running (required for the attack surface, though the flaw resides in its handling of hard links)

The system is affected if it runs an affected Windows 10 or Windows Server version (1607 through 1903 for Win10, 1709/1803 for Server) and lacks the KB4493440 or corresponding monthly security update.

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
Patch available Apply the vendor patch
Vendor patch msrc.microsoft.com →
Interim mitigation

Apply the Microsoft security update (KB4493440 for Windows 10, or respective monthly rollup) that corrects how AppXSVC handles hard links.

Recommended fix High confidence

June 2019 Security Updates (KB4503276 or version-specific KB)

  1. Open Windows Update by pressing the Windows key and typing 'Windows Update'
  2. Click 'Check for updates' to download and install the latest security updates
  3. Alternatively, manually download the security update from the Microsoft Security Update Guide at msrc.microsoft.com
  4. Search for CVE-2019-1064 and download the appropriate update for your Windows version
  5. Install the update and restart the system if prompted
  6. Verify the update was installed by checking Windows Update history

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

Fix this in Windows 10 1607 Exploited in the wild — priority engagement
  • Consultation2.0 h
  • Implementation2.0 h
  • Testing2.0 h
  • Review / QA1.0 h
7.0 hours of engineering $1,240
Get it fixed fast

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,984.

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-2019-1064 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