CVE-2011-1231
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 · uneditedwin32k.sys in the kernel-mode drivers in Microsoft Windows XP SP2 and SP3, Windows Server 2003 SP2, Windows Vista SP1 and SP2, Windows Server 2008 Gold, SP2, R2, and R2 SP1, and Windows 7 Gold and SP1 allows local users to gain privileges via a crafted application that triggers a NULL pointer dereference, a different vulnerability than other "Vulnerability Type 2" CVEs listed in MS11-034, aka "Win32k Null Pointer De-reference 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 confidenceA NULL pointer dereference vulnerability in win32k.sys (kernel-mode driver) allows local authenticated users to elevate privileges to SYSTEM level by triggering the NULL pointer dereference through a specially crafted application. The vulnerability affects Windows XP SP2/SP3, Server 2003 SP2, Vista SP1/SP2, Server 2008 (all variants), and Windows 7 Gold/SP1.
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 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
- Local
- Complexity
- Low
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:L/AC:L/PR:N/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 versionRun 'winver' or check System Properties to confirm the Windows version and SP levelAffected if The system is running Windows XP (any SP), Windows Server 2003 (any version), Windows Vista (any SP), Windows Server 2008/2008 R2 (any version), or Windows 7/7 SP1
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Check if MS11-034 security update is installedOpen Control Panel > Programs and Features > View installed updates, or run 'wmic qfe list' command to list installed hotfixes, and search for KB956802 or KB977165Affected if The security update MS11-034 (KB956802 or KB977165) is NOT installed
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Verify win32k.sys versionNavigate to C:\Windows\System32\drivers\win32k.sys, right-click > Properties > Details to view file version, or run 'driverquery /v | findstr win32k'Affected if The win32k.sys version is older than the patched version for the respective Windows version (unpatched versions are vulnerable)
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Confirm local access existsVerify that an untrusted local user account exists on the system (run 'net user' to list local users)Affected if An untrusted local user account is present and can execute code on the system, allowing them to trigger the crafted exploit
The system is vulnerable if it runs an affected Windows version (XP, Server 2003, Vista, Server 2008, Windows 7) AND lacks the MS11-034 security update, allowing a local authenticated user to potentially escalate privileges to SYSTEM.
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 update MS11-034, which patches the win32k.sys kernel-mode driver to properly handle pointer references and prevent NULL pointer dereference exploitation.
- Consultation2.0 h
- Implementation3.0 h
- Testing4.0 h
- Review / QA1.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2011-1231 — 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-2011-1231 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