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Windows 10Operating system · Microsoft

CVE-2018-8339

HIGH · 7.0 CVSS v3.0 Published 2018-08-15
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
72/100
Remediation priority · Elevated
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
An elevation of privilege vulnerability exists in the Windows Installer when the Windows Installer fails to properly sanitize input leading to an insecure library loading behavior, aka "Windows Installer Elevation of Privilege Vulnerability." This affects Windows 7, Windows Server 2012 R2, Windows RT 8.1, Windows Server 2008, Windows Server 2012, Windows 8.1, Windows Server 2016, Windows Server 2008 R2, Windows 10, Windows 10 Servers.

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 an insecure library loading (DLL hijacking) vulnerability in the Windows Installer service. The Windows Installer fails to properly sanitize input, allowing an attacker to cause malicious DLL libraries to be loaded, leading to elevation of privilege from a low-privilege user context.

MitigationApply the Microsoft security update for CVE-2018-8339 to patch the Windows Installer insecure library loading vulnerability. Prioritize patching endpoint systems and servers as specified in Microsoft's security bulletin.

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 10Operating system
Affected:all versions= 1607= 1703= 1709= 1803
Windows 7Operating system
Affected:all versions
Windows 8.1Operating system
Affected:all versions
Windows Rt 8.1Operating system
Affected:all versions
Windows Server 2008Operating system
Affected:all versions= r2
Windows Server 2012Operating system
Affected:all versions= r2
Windows Server 2016Operating system
Affected:all versions= 1709= 1803

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
High
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.0/AV:L/AC:H/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 list
    Run 'winver' or 'systeminfo | findstr /B /C:"OS Name" /C:"OS Version"' to identify the Windows version and build number
    Affected if The system runs Windows 7, 8.1, RT 8.1, Windows 10 (any version), Windows Server 2008, 2012, 2012 R2, or 2016 without the CVE-2018-8339 patch installed
  2. Verify Windows Installer version
    Check the version of msiexec.exe at %SystemRoot%\System32\msiexec.exe by right-clicking the file, selecting Properties, and viewing the Details tab
    Affected if The Windows Installer version is older than the patched version for CVE-2018-8339 (compare against Microsoft's security update KB4457903 or subsequent updates)
  3. Confirm security update installation status
    Open Control Panel > Programs and Features > View installed updates, or run 'wmic qfe list' command, and search for the KB patch related to CVE-2018-8339
    Affected if The security update for CVE-2018-8339 is NOT listed among installed updates
  4. Check for vulnerable DLL loading paths
    Inspect the Windows Installer service configuration and associated temporary directories for world-writable locations where low-privilege users could place malicious DLL files
    Affected if The system allows low-privilege users to write to directories that Windows Installer uses for DLL loading without proper path validation

The system is affected if it runs any of the affected Windows versions (7, 8.1, 10, Server 2008/2012/2016) and lacks the CVE-2018-8339 security update, allowing potential DLL hijacking via Windows Installer.

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.

From vendor data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Apply the Microsoft security update for CVE-2018-8339 to patch the Windows Installer insecure library loading vulnerability. Prioritize patching endpoint systems and servers as specified in Microsoft's security bulletin.

Fix this in Windows 10 Scoped from the published advisory
  • Consultation8.0 h
  • Implementation16.0 h
  • Testing12.0 h
  • Review / QA8.0 h
44.0 hours of engineering $7,720
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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-2018-8339 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