CVE-2009-2524
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 · uneditedInteger underflow in the NTLM authentication feature in the Local Security Authority Subsystem Service (LSASS) in Microsoft Windows XP SP2 and SP3, Windows Server 2003 SP2, Windows Vista Gold, SP1, and SP2, Windows Server 2008 Gold, SP2, and R2, and Windows 7 allows remote attackers to cause a denial of service (reboot) via a malformed packet, aka "Local Security Authority Subsystem Service Integer Overflow 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 confidenceInteger underflow vulnerability in the NTLM authentication handler within LSASS allows remote unauthenticated attackers to send malformed packets that trigger a system reboot (denial of service). The vulnerability exists in how LSASS processes NTLM authentication requests before validating credentials.
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 versionsall versionsall versionsall 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
- Authentication
- None
- Confidentiality
- None
- Integrity
- None
- Availability
- Complete
AV:N/AC:L/Au:N/C:N/I:N/A:C
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 versionRun 'winver' or check System Properties to confirm the Windows version. For command-line, use 'systeminfo | findstr /B /C:"OS Name" /C:"OS Version"'Affected if The version is Windows XP, Windows Vista, Windows 7, Windows Server 2003, or Windows Server 2008 - all of which are in the affected list
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Verify NTLM authentication is enabledCheck the Network Security: LAN Manager authentication level policy (secpol.msc) or registry key HKLM\SYSTEM\CurrentControlSet\Control\Lsa\LmCompatibilityLevel. Values 0-3 enable NTLM authentication.Affected if NTLM (LM/NTLM responses) is enabled (value 0-3) - the vulnerability exists in the NTLM authentication handler before credential validation
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Confirm LSASS service is runningOpen Services console (services.msc) or run 'sc query lsass' to verify the Local Security Authority Subsystem Service is activeAffected if LSASS service is running - this is the component that contains the vulnerable NTLM handler
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Check if MS09-055 patch is installedRun 'wmic qfe list' or check Windows Update history for security update KB968537 (MS09-055)Affected if The MS09-055 patch is NOT installed - this is the specific update that addresses this vulnerability in affected systems
A system is affected if it runs an unpatched Windows XP/Vista/7/2003/2008 version with NTLM authentication enabled and the LSASS service running, making it vulnerable to remote unauthenticated DoS via malformed NTLM packets.
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 (MS09-055 or subsequent relevant patches) to all affected Windows systems. For end-of-life systems that cannot be patched, disable NTLM authentication in favor of Kerberos, implement network segmentation to limit exposure, or migrate to supported Windows versions.
- Consultation2.0 h
- Implementation4.0 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-2009-2524 — 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-2009-2524 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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- Version or environment caveats, and links to real fixes
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