CVE-2017-8542
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 · uneditedThe Microsoft Malware Protection Engine running on Microsoft Forefront and Microsoft Defender on Microsoft Windows Server 2008 SP2 and R2 SP1, Windows 7 SP1, Windows 8.1, Windows Server 2012 Gold and R2, Windows RT 8.1, Windows 10 Gold, 1511, 1607, and 1703, and Windows Server 2016, Microsoft Exchange Server 2013 and 2016, does not properly scan a specially crafted file leading to denial of service. aka "Microsoft Malware Protection Engine Denial of Service Vulnerability", a different vulnerability than CVE-2017-8535, CVE-2017-8536, CVE-2017-8537, and CVE-2017-8539.
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 confidenceThe Microsoft Malware Protection Engine fails to properly scan specially crafted files, causing a denial of service condition. When the engine attempts to parse a malformed file, it becomes unresponsive or crashes, affecting both Windows Defender/Forefront on client and server systems as well as Microsoft Exchange Server 2013 and 2016.
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 dataall versions<= 1.1.13704.0all versionsCVSS 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
- None
- User interaction
- Required
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- High
CVSS:3.0/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/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 checksWork through these to decide whether this CVE applies to you.
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Verify Microsoft Malware Protection Engine is installedCheck if Windows Defender, Forefront Security, or Exchange server with malware protection is running. For Windows systems, open Task Manager and look for MsMpEng.exe, or run 'Get-Process MsMpEng' in PowerShell.Affected if The process MsMpEng.exe is running or the Malware Protection Engine is otherwise present on the system
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Determine the Malware Protection Engine versionOpen PowerShell and run: '$mpengine = Get-ItemProperty "HKLM:\SOFTWARE\Microsoft\Microsoft Malware Protection\CurrentVersion" -Name "EngineVersion" -ErrorAction SilentlyContinue; $mpengine.EngineVersion'Affected if The engine version returned is empty or cannot be determined via this method, try alternative version detection methods
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Check engine version using mpcmdrun utilityNavigate to C:\Program Files\Windows Defender (or %ProgramFiles%\Windows Defender) and run: MpCmdRun.exe -SignatureUpdate -VerifySignatures. The output will display the engine version.Affected if The displayed engine version is 1.1.13704.0 or lower
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Confirm version via file properties as fallbackRight-click on MsMpEng.exe in C:\Windows\System32\ (or C:\Program Files\Windows Defender\) and select Properties, then view the File Version information.Affected if The file version shown is 1.1.13704.0 or lower
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Check if running affected Microsoft Exchange versionsFor Exchange servers, run 'Get-ExchangeServer | Select-Object Name,AdminDisplayVersion' in Exchange Management Shell to identify Exchange 2013 or 2016 installations.Affected if Exchange Server 2013 or 2016 is installed and the Malware Protection Engine is enabled for email scanning
The system is affected if the Microsoft Malware Protection Engine version is 1.1.13704.0 or lower, regardless of whether Windows Defender, Forefront Security, or Exchange with protection is used.
Generated from the published advisory. Verify against your own configuration.
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 dataApply the Microsoft security update for the Malware Protection Engine via Windows Update, Microsoft Update, or enterprise patch management systems. For Exchange servers, apply the relevant cumulative update or security update that includes the engine patch.
- Consultation2.0 h
- Implementation4.0 h
- Testing2.0 h
- Review / QA1.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,560.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2017-8542 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2017-8542 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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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.
- 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