CVE-2025-29955
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 · uneditedImproper input validation in Windows Hyper-V allows an unauthorized attacker to deny service locally.
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 · low confidenceWindows Hyper-V contains an improper input validation vulnerability that allows an unauthenticated local attacker to cause a denial of service. The vulnerability stems from the hypervisor not properly validating certain inputs, which can be triggered locally to crash the Hyper-V host or cause instability.
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< 10.0.26100.4061< 10.0.25398.1611< 10.0.26100.4061CVSS 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
- None
- Integrity
- None
- Availability
- High
CVSS:3.1/AV:L/AC:L/PR:L/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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Verify Hyper-V is installedRun 'Get-WindowsOptionalFeature -Online -FeatureName Microsoft-Hyper-V-All' in PowerShell or check via 'hyperv' in systeminfo. On Server, use 'Get-WindowsFeature -Name Hyper-V'Affected if Hyper-V feature is installed or enabled on the system
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Check Windows build versionRun 'winver' or 'systeminfo | findstr /B /C:OS Version' to obtain the full build number, or use 'Get-ComputerInfo | Select-Object WindowsVersion, OsVersion, OsBuildNumber' in PowerShellAffected if Build number is less than 10.0.26100.4061 for Windows 11 24h2 or Windows Server 2025, OR less than 10.0.25398.1611 for Windows Server 2022 23h2
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Confirm edition is affectedRun 'systeminfo' or 'Get-ComputerInfo' to verify the Windows edition is one of: Windows 11 24h2, Windows Server 2022 23h2, or Windows Server 2025Affected if Running an affected edition within the version ranges specified
User is affected if Hyper-V is enabled AND the Windows build number falls below the thresholds for their specific version (26100.4061 for Win11 24h2/Server2025, 25398.1611 for Server2022 23h2).
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.
dbcve · scoped10.0.25398.161110.0.26100.4061
Apply Microsoft security updates for Windows Hyper-V when available. Ensure hypervisor hosts are patched promptly and follow least-privilege access controls to limit local attack surface.
Windows 11 24h2: 10.0.26100.4061+ | Windows Server 2022 23h2: 10.0.25398.1611+ | Windows Server 2025: 10.0.26100.4061+
- Identify the current Windows version by running 'winver' or 'systeminfo' in Command Prompt
- For Windows 11 24h2 systems: Apply Windows update KB5055627 (or later) which includes build 10.0.26100.4061
- For Windows Server 2022 23h2 systems: Apply Windows update KB5055619 (or later) which includes build 10.0.25398.1611
- For Windows Server 2025 systems: Apply Windows update KB5055627 (or later) which includes build 10.0.26100.4061
- Restart the system after applying the update
- Verify the update was successful by checking the Windows version matches or exceeds the fixed build numbers
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation2.0 h
- Implementation1.0 h
- Testing4.0 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 $2,464.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2025-29955 — 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-2025-29955 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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