CVE-2022-41056
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 · uneditedNetwork Policy Server (NPS) RADIUS Protocol Denial of Service 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 · high confidenceThis is a denial of service vulnerability in Microsoft's Network Policy Server (NPS). The vulnerability exists in how NPS handles specially crafted RADIUS protocol packets, allowing an unauthenticated remote attacker to crash the NPS service, causing authentication failures for all dependent services like VPN, Wi-Fi, and dial-up connections.
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= 21h1= 21h2= 22h2= 1607= 1809all versions= 22h2= sp1all versionsall versions= r2all versions= r2all versionsall 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
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/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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Confirm NPS role is installedOn Windows Server, open Server Manager > Manage > Add Roles and Features, or run 'Get-WindowsFeature -Name NPAS' in PowerShell. On Windows 10/11, check Programs and Features for 'Network Policy Server' or run 'Get-Service -Name IAS' to check for the Internet Authentication Service (IAS) which provides NPS functionality.Affected if NPS or IAS role/service is present on the system
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Verify Windows version is within affected rangeRun 'winver' from Run dialog, or run 'systeminfo | findstr /B /C:"OS Name" /C:"OS Version"' in Command Prompt, or run 'Get-ComputerInfo | Select WindowsProductName, WindowsVersion' in PowerShell.Affected if The Windows version matches any of the affected versions listed (Windows 10 20h2/21h1/21h2/22h2/1607/1809, Windows 11 22h2, Windows 7 SP1, Windows 8.1, Windows Server 2008/2008R2/2012/2012R2/2016/2019)
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Confirm NPS service is running and enabledRun 'Get-Service -Name "Network Policy Server"' (or 'net start "Network Policy Server"' to check if it can be started) in PowerShell, or open Services and look for 'Network Policy Server' (NPS).Affected if The NPS service is installed and set to start (Automatic or Manual)
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Assess network exposure of RADIUS portsRun 'netsh advfirewall firewall show rule name=all | findstr /C:"1812" /C:"1813" /C:"1645" /C:"1646"' to list firewall rules for RADIUS ports, or check external firewall rules that allow UDP ports 1812, 1813, 1645, 1646 from untrusted sources.Affected if RADIUS ports (UDP 1812, 1813, 1645, 1646) are open to untrusted or internet-facing network interfaces
The system is affected if NPS is installed and running on a vulnerable Windows version, and the server is accessible to untrusted networks on RADIUS ports.
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 (KB5020012 or later for Windows Server) to the affected NPS servers. If immediate patching is not feasible, restrict RADIUS access to trusted networks via firewall rules to reduce attack surface.
- Consultation2.0 h
- Implementation2.0 h
- Testing2.0 h
- Review / QA1.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2022-41056 — 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-2022-41056 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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- 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
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