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Actively exploited in the wild. This CVE is on the CISA Known Exploited Vulnerabilities list — treat remediation as urgent. Federal remediation due by 21 Apr 2022.
Windows 7Operating system · Microsoft

CVE-2010-4398

HIGH · 7.8 CVSS v3.1 Published 2010-12-06
Patch available
A vendor patch is available. No clean upgrade release — apply the published patch.
See remediation →
96/100
Remediation priority · Urgent
In the wild Public exploit Zero-click Patch available

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 · unedited
Stack-based buffer overflow in the RtlQueryRegistryValues function in win32k.sys in Microsoft Windows XP SP2 and SP3, Windows Server 2003 SP2, Windows Vista SP1 and SP2, Windows Server 2008 Gold, SP2, and R2, and Windows 7 allows local users to gain privileges, and bypass the User Account Control (UAC) feature, via a crafted REG_BINARY value for a SystemDefaultEUDCFont registry key, aka "Driver Improper Interaction with Windows Kernel 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 confidence

Stack-based buffer overflow in win32k.sys's RtlQueryRegistryValues function allows local authenticated users to gain elevated privileges and bypass UAC by inserting a specially crafted REG_BINARY value into the SystemDefaultEUDCFont registry key, causing kernel-mode memory corruption.

MitigationApply Microsoft security bulletin MS10-098 (KB2423089) to patch the vulnerable win32k.sys driver, or restrict write access to the SystemDefaultEUDCFont registry key for standard users.

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
Windows 7Operating system
Affected:all versions
Windows Server 2003Operating system
Affected:all versions
Windows Server 2008Operating system
Affected:all versions= r2
Windows VistaOperating system
Affected:all versions
Windows XpOperating system
Affected:all versions

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.

From the vector
Attack vector
Local
Complexity
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/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 checks

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

  1. Identify Windows version
    Run 'winver' or check System Properties to confirm the Windows version. Affected versions are Windows XP, Vista, 7, Server 2003, and Server 2008/R2.
    Affected if The system runs an unpatched version of Windows XP, Vista, 7, Server 2003, or Server 2008/R2.
  2. Check for security update KB2423089
    Open Control Panel > Programs > View installed updates and search for 'KB2423089', or run 'wmic qfe list | findstr 2423089'
    Affected if KB2423089 is NOT installed - the system is missing the patch that fixes this vulnerability.
  3. Inspect SystemDefaultEUDCFont registry key
    Navigate to HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\SystemDefaultEUDCFont in Registry Editor, or run 'reg query "HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\SystemDefaultEUDCFont"'
    Affected if The registry key exists and contains a REG_BINARY value (especially one with unusual or long binary data), indicating a possible exploit attempt.
  4. Check write permissions on the registry key
    Right-click the SystemDefaultEUDCFont key in Registry Editor, select Permissions, and verify which users have Write permission. Or check with 'reg query' and access control listings.
    Affected if Standard (non-admin) users have Write access to this registry key, which would allow them to exploit the vulnerability.

The system is affected if it runs an unpatched Windows version (XP/Vista/7/Server 2003/Server 2008) without KB2423089 AND the SystemDefaultEUDCFont registry key exists with a REG_BINARY value that standard users can modify.

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

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

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 · scoped
Patch available Apply the vendor patch
Vendor patch docs.microsoft.com →
Interim mitigation

Apply Microsoft security bulletin MS10-098 (KB2423089) to patch the vulnerable win32k.sys driver, or restrict write access to the SystemDefaultEUDCFont registry key for standard users.

Recommended fix High confidence

If patches are unavailable for your Windows version (e.g., Windows XP, Windows Server 2003 are end-of-life), upgrade to a supported Windows version such as Windows 10 or Windows Server 2016 and later

  1. Locate and apply Microsoft Security Update MS10-083, which addresses this vulnerability in the Windows Kernel (win32k.sys)
  2. Verify the update is successfully installed by checking Windows Update history or reviewing installed updates
  3. Restart the system as required by the update
  4. Confirm the SystemDefaultEUDCFont registry key in HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Fonts does not contain unexpectedly large REG_BINARY values as a post-install check
Caveat Applying kernel updates may require system restart and could have compatibility implications with third-party drivers; ensure backup and test in non-production environment first

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Windows 7 Exploited in the wild — priority engagement
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing3.0 h
  • Review / QA1.0 h
10.0 hours of engineering $1,750
Get it fixed fast

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

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

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2010-4398 in production — separate from our analysis above.

No notes yet

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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