dbcve.org
Windows 10Operating system · Microsoft

CVE-2018-8349

HIGH · 8.8 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 →
95/100
Remediation priority · Urgent
Remotely reachable No privileges

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
A remote code execution vulnerability exists in "Microsoft COM for Windows" when it fails to properly handle serialized objects, aka "Microsoft COM for Windows Remote Code Execution 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

A remote code execution vulnerability exists in Microsoft COM for Windows due to improper handling of serialized objects. An attacker who successfully exploits this vulnerability could execute arbitrary code in the context of the current user. The vulnerability affects multiple Windows versions from Windows 7 through Windows 10 and various Windows Server editions.

MitigationApply the relevant Microsoft security updates (KB4343909 and related patches from August 2018) to all affected Windows systems. Prioritize externally-facing servers and systems with privileged users.

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
Network
Complexity
Low
Privileges
None
User interaction
Required
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.0/AV:N/AC:L/PR:N/UI:R/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
    Run 'winver' from command prompt or check HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion for the 'CurrentBuild' and 'DisplayVersion' values
    Affected if The installed version is Windows 10 (any version, particularly 1607, 1703, 1709, 1803), Windows 7, Windows 8.1, Windows Rt 8.1, Windows Server 2008, Windows Server 2012, or Windows Server 2016 - these are within the affected product list
  2. Verify security update KB4343909 is installed
    Run 'wmic qfe list' or check 'Get-HotFix -Id KB4343909' in PowerShell to see if the August 2018 security update is applied
    Affected if The KB4343909 update is NOT installed - the system remains vulnerable to CVE-2018-8349
  3. Check alternate August 2018 security patches
    Run 'wmic qfe list' and look for any August 2018 security updates for Windows, as Microsoft released multiple related patches for this vulnerability
    Affected if No August 2018 security updates are present in the installed updates list for the affected Windows version
  4. Confirm COM component is present
    Verify the Windows COM infrastructure is present by checking that 'C:\Windows\System32\ole32.dll' and 'C:\Windows\System32\combase.dll' exist (these contain the vulnerable COM deserialization code)
    Affected if These COM DLL files exist and no August 2018 security patches have been applied - the vulnerability is present
  5. Check Windows 7/Server 2008 R2 specific patch
    For Windows 7 and Windows Server 2008 R2, also verify KB4343909 or the combined rollup updates from August 2018 are installed
    Affected if Running Windows 7 or Server 2008 R2 without the August 2018 security rollup installed

A system is affected if it runs any affected Windows version (Windows 7, 8.1, 10, Server 2008, 2012, or 2016) AND lacks the August 2018 security updates (particularly KB4343909) that address the COM deserialization vulnerability.

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 relevant Microsoft security updates (KB4343909 and related patches from August 2018) to all affected Windows systems. Prioritize externally-facing servers and systems with privileged users.

Fix this in Windows 10 Scoped from the published advisory
  • Consultation4.0 h
  • Implementation12.0 h
  • Testing6.0 h
  • Review / QA3.0 h
25.0 hours of engineering $4,400
Get help mitigating

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $7,040.

Scan for this in your stack

Free · runs locally
dbcve dependency scanner

Check whether your project pulls in CVE-2018-8349 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.

Get it on GitHub Scan in the browser

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-2018-8349 in production — separate from our analysis above.

No notes yet

Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.

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