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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 18 Apr 2022.
Windows 10 1809Operating system · Microsoft

CVE-2021-34486

HIGH · 7.8 CVSS v3.1 Published 2021-08-12
Fix available
A fix is available. Upgrade to 10.0.17763.2114 / 10.0.18363.1734 or later.
See remediation →
96/100
Remediation priority · Urgent
In the wild 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
Windows Event Tracing Elevation of Privilege Vulnerability

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

This is a Windows Elevation of Privilege vulnerability in the Windows Event Tracing component. The vulnerability allows a local attacker to gain elevated privileges on the affected system, potentially executing arbitrary code with higher privileges than the attacker normally possesses.

MitigationApply the relevant Microsoft security updates for Windows to address this vulnerability. Organizations should ensure Windows systems are patched through their standard update management processes.

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:< 10.0.17763.2114
Windows 10 1909Operating system
Affected:< 10.0.18363.1734
Windows 10 2004Operating system
Affected:< 10.0.19041.1165
Windows 10 20h2Operating system
Affected:< 10.0.19042.1165
Windows 10 21h1Operating system
Affected:< 10.0.19043.1165
Windows Server 2004Operating system
Affected:< 10.0.19041.1165
Windows Server 2019Operating system
Affected:< 10.0.17763.2114
Windows Server 20h2Operating system
Affected:< 10.0.19042.1165

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. Determine Windows build version
    Run 'winver' or 'systeminfo' from command prompt, or execute 'reg query "HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion" /v CurrentBuild'
    Affected if Build number is below 17763.2114 (Windows 10 1809/Server 2019), 18363.1734 (Windows 10 1909), 19041.1165 (Windows 10 2004/Server 2004), 19042.1165 (Windows 10 20h2/Server 20h2), or 19043.1165 (Windows 10 21h1)
  2. Verify Event Tracing service status
    Run 'sc query EventLog' from command prompt to confirm Windows Event Log service is running, as Event Tracing depends on this
    Affected if Event Logging service is running (vulnerability is present in the ETW component when this service is active)
  3. Confirm security update installation
    Run 'wmic qfe list' or 'Get-HotFix | Where-Object {$_.HotFixID -eq "KB5005033"}' from command prompt or PowerShell
    Affected if The specific security update for CVE-2021-34486 (KB5005033 or later cumulative update) is NOT installed

Your system is affected if it runs an unpatched Windows 10 or Windows Server version within the affected build ranges and has the Windows Event Log/Event Tracing service enabled.

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 10.0.17763.2114 / 10.0.18363.1734 / 10.0.19041.1165 or later
Fixed in 10.0.17763.211410.0.18363.173410.0.19041.1165
Vendor patch portal.msrc.microsoft.com →
Interim mitigation

Apply the relevant Microsoft security updates for Windows to address this vulnerability. Organizations should ensure Windows systems are patched through their standard update management processes.

Recommended fix High confidence

Windows 10 1809: >= 10.0.17763.2114 | Windows 10 1909: >= 10.0.18363.1734 | Windows 10 2004: >= 10.0.19041.1165 | Windows 10 20h2: >= 10.0.19042.1165 | Windows 10 21h1: >= 10.0.19043.1165 | Windows Server 2004: >= 10.0.19041.1165 | Windows Server 2019: >= 10.0.17763.2114 | Windows Server 20h2: >= 10

  1. Identify the current Windows version by running 'winver' or 'systeminfo' in Command Prompt
  2. Determine which version range your system falls into from the affected versions list
  3. Open Settings > Update & Security > Windows Update or run 'ms-settings:windowsupdate'
  4. Check for updates and install the security update for August 2021 or later
  5. Alternatively, manually download the specific security update from the Microsoft Update Catalog by searching for CVE-2021-34486
  6. Restart the system after the update is installed
  7. Verify the fix by checking the installed updates list or running 'winver' to confirm the version matches or exceeds the fixed version for your product
Caveat Windows security updates typically have minimal breaking changes; ensure critical applications are tested after patching

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

Fix this in Windows 10 1809 Exploited in the wild — priority engagement
  • Consultation2.0 h
  • Implementation1.0 h
  • Testing2.0 h
  • Review / QA1.0 h
6.0 hours of engineering $1,060
Get it fixed fast

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,696.

Scan for this in your stack

Free · runs locally
dbcve dependency scanner

Check whether your project pulls in CVE-2021-34486 — 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-2021-34486 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