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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 22 Jun 2022.
OfficeApplication · Microsoft

CVE-2009-0557

HIGH · 7.8 CVSS v3.1 Published 2009-06-10
Patch available
A vendor patch is available. No clean upgrade release — apply the published patch.
See remediation →
97/100
Remediation priority · Urgent
In the wild High EPSS No privileges 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
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; and Microsoft Office Compatibility Pack for Word, Excel, and PowerPoint 2007 File Formats SP1 and SP2 allow remote attackers to execute arbitrary code via a crafted Excel file with a malformed record object, aka "Object Record Corruption 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

Memory corruption vulnerability in Microsoft Excel where a crafted Excel file containing a malformed record object triggers heap corruption, allowing an attacker to execute arbitrary code via the specially crafted file.

MitigationDeploy the Microsoft security update MS09-021 to all affected Office installations; until patched, warn users not to open Excel files from untrusted sources and consider enabling Office File Validation as a defense-in-depth control.

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
OfficeApplication
Affected:= 2000= 2003= 2004= 2007= 2008= xp
Office Compatibility PackApplication
Affected:= 2007
Office Excel ViewerApplication
Affected:all versions= 2003
Office Sharepoint ServerApplication
Affected:= 2007
Open Xml File Format ConverterApplication
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
None
User interaction
Required
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:L/AC:L/PR:N/UI:R/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. Check installed Excel version
    Locate the Excel executable (excel.exe) in the Office program directory (typically C:\Program Files\Microsoft Office\OfficeXX\ or C:\Program Files (x86)\Microsoft Office\OfficeXX\) and view its file properties to see the version number, or query the registry under HKLM\SOFTWARE\Microsoft\Office\{version}\Excel\InstallRoot for the installed path and version
    Affected if The installed Excel version falls within these affected ranges: Office 2000, Office 2003, Office XP (2002), Office 2004 (Mac), Office 2007, Office 2008 (Mac)
  2. Check Office Compatibility Pack version
    If the Compatibility Pack is installed, locate the Excel converter executable (xlconv.exe) in the Compatibility Pack directory (typically C:\Program Files\Microsoft Office\Office12\) and check its version; also check registry under HKLM\SOFTWARE\Microsoft\Office\12.0\Compatibility Pack\InstallRoot
    Affected if The Compatibility Pack version is 2007 (version 12.0)
  3. Check Excel Viewer installation
    Check for Excel Viewer (xlview.exe) in the Microsoft Office folder under Program Files; view its version properties or query the registry under HKLM\SOFTWARE\Microsoft\Office\{version}\Excel\InstallRoot for Excel Viewer entries
    Affected if Any version of Microsoft Office Excel Viewer is installed, including version 2003
  4. Check SharePoint Server 2007 presence
    Check if Microsoft Office SharePoint Server 2007 is installed by looking for SharePoint components in the registry under HKLM\SOFTWARE\Microsoft\Office Server\12.0 or by locating OfficeServer.exe in the program files
    Affected if Microsoft Office SharePoint Server 2007 is installed
  5. Check Open XML File Format Converter
    Locate the Open XML File Format Converter (oxfc.exe or converter.exe) in the program files and check its version, or check registry entries under HKLM\SOFTWARE\Microsoft\Office\Open XML File Format Converter
    Affected if The Open XML File Format Converter for Mac is installed (any version)

Your environment is affected if any Microsoft Office Excel component (Excel, Compatibility Pack, Excel Viewer, SharePoint Server 2007, or Open XML File Format Converter) matching the specific version numbers above is installed and users can open Excel files.

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.

From vendor data
Patch available Apply the vendor patch
Vendor patch docs.microsoft.com →
Interim mitigation

Deploy the Microsoft security update MS09-021 to all affected Office installations; until patched, warn users not to open Excel files from untrusted sources and consider enabling Office File Validation as a defense-in-depth control.

Fix this in Office Exploited in the wild — priority engagement
  • Consultation3.0 h
  • Implementation6.0 h
  • Testing3.0 h
  • Review / QA2.0 h
14.0 hours of engineering $2,490
Get it fixed fast

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,984.

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-2009-0557 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