CVE-2021-1658
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 · uneditedRemote Procedure Call Runtime Remote Code Execution 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 confidenceWindows RPC Runtime vulnerability allowing remote code execution, likely exploitable over network without authentication.
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= 20h2= 1607= 1803= 1809= 1909= 2004all versionsall versionsall versionsall versions= r2all versions= r2all versions= 20h2= 1909= 2004all 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
- Network
- Complexity
- Low
- Privileges
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/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 checksWork through these to decide whether this CVE applies to you.
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Identify Windows version and buildRun 'winver' or 'systeminfo | findstr /B /C:"OS Name" /C:"OS Version"' to determine your exact Windows version and build numberAffected if The version matches any of the affected products listed (Windows 10 20h2/1607/1803/1809/1909/2004, Windows 7 all versions, Windows 8.1 all versions, Windows RT 8.1, Windows Server 2008/2008 R2/2012/2012 R2/2016/2019 all versions)
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Check for installed security updatesOpen Control Panel > Programs > Programs and Features > View installed updates, or run 'wmic qfe list' to list installed hotfixesAffected if The specific KB article for CVE-2021-1658 (KB5000802 for March 2021 or subsequent related updates) is NOT installed
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Verify RPC service statusRun 'sc query rpcss' or check Services > Remote Procedure Call (RPC) and Remote Procedure Call (RPC) Locator in services.mscAffected if The RPC service is running (this is the default state and required for the vulnerability to be exploitable; if disabled, the attack surface is reduced)
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Check network listening portsRun 'netstat -an | findstr "135 445 593"' to see if RPC-related ports are listeningAffected if RPC Endpoint Mapper (135) or other RPC ports are open and accessible on network interfaces (especially externally-facing)
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Confirm patch level via PowerShellRun 'Get-HotFix | Where-Object {$_.Description -like "Security Update"} | Sort-Object InstalledOn -Descending | Select-Object -First 10' to list recent security updatesAffected if No security updates from March 2021 or later are installed, indicating the system has not received the CVE-2021-1658 patch
A system is likely affected if it runs any affected Windows version listed and is missing the March 2021 or later security updates for CVE-2021-1658, with RPC services enabled and accessible.
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 Microsoft security updates for CVE-2021-1658; prioritize immediate patching given RCE capability and high CVSS score.
- Consultation2.0 h
- Implementation4.0 h
- Testing3.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,088.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-1658 — 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-2021-1658 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