CVE-2009-0561
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 overflow in Excel in Microsoft Office 2000 SP3, Office XP SP3, Office 2003 SP3, and Office 2004 and 2008 for Mac; Excel in 2007 Microsoft Office System SP1 and SP2; Open XML File Format Converter for Mac; Microsoft Office Excel Viewer 2003 SP3; Microsoft Office Excel Viewer; Microsoft Office Compatibility Pack for Word, Excel, and PowerPoint 2007 File Formats SP1 and SP2; and Microsoft Office SharePoint Server 2007 SP1 and SP2 allows remote attackers to execute arbitrary code via an Excel file with a Shared String Table (SST) record with a numeric field that specifies an invalid number of unique strings, which triggers a heap-based buffer overflow, aka "Record 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 overflow vulnerability in Microsoft Excel's Shared String Table (SST) record parsing. When an Excel file contains a malformed SST record with an invalid number of unique strings specified in a numeric field, it triggers a heap-based buffer overflow allowing remote code execution.
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= 2004= 2008= xpall versions= 2000= 2003= 2007all versions= 2003= 2007all 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
- M
- Authentication
- None
- Confidentiality
- Complete
- Integrity
- Complete
- Availability
- Complete
AV:N/AC:M/Au:N/C:C/I:C/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 installed Microsoft Office or Excel versionOpen Control Panel > Programs and Features, or right-click on Excel.exe (typically in C:\Program Files\Microsoft Office\OfficeXX or C:\Program Files (x86)\Microsoft Office\OfficeXX) and select Properties > Details to view the version numberAffected if Version is 2000, 2003, 2004, 2007, 2008, or xp without subsequent security patches applied after MS09-021
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Check for installed Excel ViewerLook in Programs and Features for Microsoft Office Excel Viewer, or check the installation directory typically at C:\Program Files\Microsoft Office\Excel ViewerAffected if Excel Viewer of any version is installed and unpatched
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Verify SharePoint Server 2007 presenceCheck Programs and Features for Microsoft Office SharePoint Server 2007, or check server components via Programs and FeaturesAffected if SharePoint Server 2007 is installed and the Excel parsing component is accessible to users uploading Excel files
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Check Open XML File Format Converter installationLook in Programs and Features for Microsoft Office Open XML File Format Converter, or check for the converter application in the installation directoryAffected if Open XML File Format Converter of any version is installed and can process Excel files
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Confirm Excel file handling is exposedDetermine if the system automatically parses or previews Excel files from external sources, such as email attachments, web uploads, or document management system importsAffected if Users can directly open or the system automatically processes Excel files without sanitization or sandboxing of the SST record parsing component
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Check for MS09-021 security updateOpen Windows Update history or check Add/Remove Programs for security update KB969685 (Office 2000/2003) or KB969682 (Office 2007), or run: wmic qfe list | findstr "969685 OR 969682"Affected if The specific MS09-021 security update for this CVE is NOT installed
The environment is affected if any unpatched version of Microsoft Office Excel 2000/2003/2007, Excel Viewer, Office 2004/2008/xp, SharePoint Server 2007, Compatibility Pack, or Open XML File Format Converter is installed and users can open or process Excel files from external sources.
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 · scopedApply Microsoft security updates (MS09-021 or subsequent cumulative updates) to all affected Office installations. Until patched, restrict opening Excel files from untrusted sources and disable the Excel file handler in email gateways.
Microsoft Office 2007 Service Pack 3 or Microsoft Office 2010 (note: Office 2007 SP3 was released after this vulnerability)
- 1. Identify the exact version of Microsoft Office or Excel-dependent product installed (Office version, Service Pack level)
- 2. For Office Excel 2000 SP3: No patch available; Microsoft recommends upgrading to a supported version
- 3. For Office Excel 2002 SP3: Apply security update KB969683 from Microsoft Security Bulletin MS09-021
- 4. For Office Excel 2003 SP3: Apply security update KB969680 from MS09-021
- 5. For Office Excel 2007 SP1 or SP2: Apply security update KB969682 from MS09-021
- 6. For Office 2004 for Mac: Apply security update KB969661 from MS09-021
- 7. For Office 2008 for Mac: Apply security update KB969662 from MS09-021
- 8. For Open XML File Format Converter for Mac: Apply KB969662 (same as Office 2008 for Mac)
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation4.0 h
- Implementation8.0 h
- Testing4.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $5,120.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2009-0561 — 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-2009-0561 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