CVE-2025-53809
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 Local Security Authority Subsystem Service (LSASS) allows an authorized attacker to deny service over a network.
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 confidenceImproper input validation in Windows LSASS allows an authenticated attacker to send specially crafted network requests that cause the LSASS service to become unresponsive or crash, resulting in denial of service. This affects the core Windows authentication subsystem.
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< 10.0.26100.6508< 10.0.26100.6508CVSS 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
- None
- Integrity
- None
- Availability
- High
CVSS:3.1/AV:N/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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Check Windows version and build numberOpen Command Prompt or PowerShell and run: winver or systeminfo | findstr /B /C:"OS Name" /C:"OS Version" /C:"Build Number"Affected if The system is Windows 11 version 24h2 or Windows Server 2025 with build number below 10.0.26100.6508
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Verify exact build via PowerShellRun in PowerShell: [System.Environment]::OSVersion.Version or (Get-ItemProperty -Path 'HKLM:\SOFTWARE\Microsoft\Windows NT\CurrentVersion').CurrentBuildNumberAffected if Build number returned is less than 26100, or between 26100.0 and 26100.6507 (inclusive)
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Confirm LSASS service statusRun in Command Prompt: sc query lsass or in PowerShell: Get-Service -Name lsassAffected if LSASS service exists and is running (required for this DoS to be relevant)
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Identify if system is a domain controller or authentication serverRun: netdom /query /domain or check System Information under Computer Role for "Primary Domain Controller" or "Domain Controller"Affected if System is a domain controller or critical authentication infrastructure, as this is the likely target for authenticated attackers
A system is affected if it runs Windows 11 24h2 or Windows Server 2025 with build below 10.0.26100.6508 and LSASS is accessible to authenticated network attackers.
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 · scoped10.0.26100.6508
Apply Microsoft security updates for Windows when released. Implement network segmentation and restrict network access to domain controllers and critical authentication infrastructure to limit exposure to authorized attackers.
Windows 11 24h2 and Windows Server 2025: build 10.0.26100.6508 or later
- Check current Windows version by running 'winver' or 'systeminfo' in Command Prompt
- Open Settings > Windows Update > Check for updates
- Install the available security update that includes build 10.0.26100.6508 or higher
- Restart the system to complete the update installation
- Verify the installation by checking the Windows version again to confirm it shows 10.0.26100.6508 or later
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation2.0 h
- Implementation4.0 h
- Testing3.0 h
- Review / QA1.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,800.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2025-53809 — 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-2025-53809 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
- No spam, self-promotion, credentials, or personal data