Windows 2000Operating system · Microsoft

CVE-2006-6696

MEDIUM · 6.9 CVSS v2.0 Published 2006-12-22

Mitigation only

No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.

See remediation →

74/100

Remediation priority · Elevated

No privileges Zero-click

Official description

NVD · unedited

Double free vulnerability in Microsoft Windows 2000, XP, 2003, and Vista allows local users to gain privileges by calling the MessageBox function with a MB_SERVICE_NOTIFICATION message with crafted data, which sends a HardError message to Client/Server Runtime Server Subsystem (CSRSS) process, which is not properly handled when invoking the UserHardError and GetHardErrorText functions in WINSRV.DLL.

Technical summary

dbcve analysis · high confidence

A double-free vulnerability in Windows 2000, XP, 2003, and Vista allows local users to escalate privileges by calling the MessageBox function with MB_SERVICE_NOTIFICATION and crafted data. This sends a specially crafted HardError message to the CSRSS process, which fails to properly handle the data in WINSRV.DLL's UserHardError and GetHardErrorText functions, leading to memory corruption that can be exploited for local privilege escalation.

MitigationApply available Microsoft patches for this vulnerability; for end-of-life Windows versions (2000, XP, 2003), upgrade to supported operating systems or implement compensating controls such as restricting local access and isolating affected systems.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions

NVD · CPE data

Windows 2000Operating system

Affected:all versions

Windows 2003 ServerOperating system

Affected:= datacenter_edition= enterprise_edition= sp1= standard= web

Windows VistaOperating system

Affected:all versions

Windows XpOperating system

Affected:all versions

CVSS breakdown

From the vector

Attack vector: Local
Complexity: M
Authentication: None
Confidentiality: Complete
Integrity: Complete
Availability: Complete

AV:L/AC:M/Au:N/C:C/I:C/A:C

Am I affected?

dbcve checks

Work through these to decide whether this CVE applies to you.

Identify Windows version

Run 'winver' from command prompt or check System Properties to determine the exact Windows version and build number

Affected if The version is Windows 2000 (any), Windows XP (any), Windows 2003 Server (datacenter, enterprise, SP1, standard, or web edition), or Windows Vista (any)
Confirm CSRSS process is running

Open Task Manager, go to Processes tab, enable 'Show processes from all users', and verify that csrss.exe is present

Affected if csrss.exe is running (this process is always active on affected Windows versions and contains the vulnerable functions)
Check for third-party applications using MB_SERVICE_NOTIFICATION

Review any custom or third-party software that may call MessageBox with the MB_SERVICE_NOTIFICATION flag (0x00000020)

Affected if Any application or service on the system makes calls to MessageBox with MB_SERVICE_NOTIFICATION flag

You are affected if your Windows version matches one of the affected editions listed (2000 any, XP any, 2003 specific editions, Vista any) and any code on the system uses the MessageBox API with MB_SERVICE_NOTIFICATION flag to trigger the HardError handling path in CSRSS.

Generated from the published advisory. Verify against your own configuration.

Remediation

From vendor data

Mitigation available No clean upgrade yet — mitigate in the meantime

Mitigation

Apply available Microsoft patches for this vulnerability; for end-of-life Windows versions (2000, XP, 2003), upgrade to supported operating systems or implement compensating controls such as restricting local access and isolating affected systems.

Fix this in Windows 2000 Scoped from the published advisory

Consultation8.0 h
Implementation16.0 h
Testing8.0 h
Review / QA4.0 h

36.0 hours of engineering $6,400

Get help mitigating

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $10,240.

Scan for this in your stack

Free · runs locally

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References

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2006-6696 in production — separate from our analysis above.

Notes0 Guidelines

Know something about CVE-2006-6696?

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

Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.

What this is

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.

What belongs here

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

At a glance

A fix existsA vendor remedy is published

Severity 6.9 Medium

Exploit likelihood EPSS, next 30 days 3.4%

Affects: Windows 2000

Remediation

Need this fixed?

Fix this in Windows 2000 36 hrs · High

Typical engagement from $6,400

Get a fix See the full breakdown ↓

We specialise in CVE remediation. Send your environment and we’ll scope CVE-2006-6696 and return a fixed quote.

You’ll deal with our team directly and deploy the reviewed fix to staging first — never straight to production.

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.

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.

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.

CVSS 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.

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.

Check your environment

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.

Scan for this in your stack

References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Practitioner notes

No notes yet

Official description

Technical summary

Affected products & versions

CVSS breakdown

Am I affected?

Remediation

References