What is CVE-2009-3129?

CVE-2009-3129 is a high-severity vulnerability in Microsoft Excel, classified under Out-of-bounds Write. CVSS score: 7.8/10. Published 2009-11-11.

How severe is CVE-2009-3129?

High severity. CVSS v3 base score is 7.8 out of 10.

Is CVE-2009-3129 known to be exploited?

Yes. CVE-2009-3129 is listed in the CISA Known Exploited Vulnerabilities catalog (added 2022-03-03), indicating it is being actively exploited. 4 public proof-of-concept repositories are indexed.

Buffer overflow in Microsoft Excel

CVE-2009-3129

Microsoft Office Excel 2002 SP3, 2003 SP3, and 2007 SP1 and SP2; Office 2004 and 2008 for Mac; Open XML File Format Converter for Mac; Office Excel Viewer 2003 SP3; Office Excel Viewer SP1 and SP2; and Office Compatibility Pack for Word, Excel, and PowerPoint 2007 File Formats SP1 and SP2 allows remote attackers to execute arbitrary code via a spreadsheet with a FEATHEADER record containing an invalid cbHdrData size element that affects a pointer offset, aka "Excel Featheader Record Memory Corruption Vulnerability."

Vulnerability class: Buffer Overflow

Published 2009-11-11 · last modified 2026-06-16.

CVSS v3 metric

CVSS v3 base score 7.8 (High). Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.840 (99.7th percentile), scored 2026-10-17.

High probability of exploitation in the next 30 days — patch promptly. 100th percentile — 99.7% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.856 · newest: 0.840 · change: -0.016

Affected products

Microsoft Excel — versions 2002, 2003, 2007
Microsoft Excel Viewer — versions 2003
Microsoft Office — versions 2004, 2008
Microsoft Open XML File Format Converter

Weakness classification (CWE)

CWE-787 — Out-of-bounds Write

CISA KEV (Known Exploited Vulnerabilities)

This CVE is on the CISA KEV catalog, added on 2022-03-03. CISA KEV inclusion means CISA has confirmed in-the-wild exploitation; US federal agencies are required to remediate within a published due date.

BOD 22-01 due date: 2022-03-24.

Required action: Apply updates per vendor instructions.

Public proof-of-concept exploits

References

osvdb.org/59860 (vdb-entry, Broken Link)
oval.cisecurity.org/repository/search/definition/oval:org.mitre.oval:def:6521 (Broken Link, signature, vdb-entry)
www.securitytracker.com/id (VDB Entry, Third Party Advisory, vdb-entry, Broken Link)
www.securityfocus.com/bid/36945 (VDB Entry, Third Party Advisory, vdb-entry, Broken Link)
www.us-cert.gov/cas/techalerts/TA09-314A.html (US Government Resource, Third Party Advisory, third-party-advisory)
labs.idefense.com/intelligence/vulnerabilities/display.php (Broken Link, third-party-advisory)
docs.microsoft.com/en-us/security-updates/securitybulletins/2009/ms09-067 (vendor-advisory, Patch, Vendor Advisory)
archives.neohapsis.com/archives/bugtraq/2009-11/0080.html (mailing-list, Broken Link)
www.zerodayinitiative.com/advisories/ZDI-09-083 (VDB Entry, Third Party Advisory)
www.exploit-db.com/exploits/14706 (Exploit, VDB Entry, Third Party Advisory, exploit)

Frequently asked questions

What is CVE-2009-3129?: CVE-2009-3129 is a high-severity vulnerability in Microsoft Excel, classified under Out-of-bounds Write. CVSS score: 7.8/10. Published 2009-11-11.
How severe is CVE-2009-3129?: High severity. CVSS v3 base score is 7.8 out of 10.
Is CVE-2009-3129 known to be exploited?: Yes. CVE-2009-3129 is listed in the CISA Known Exploited Vulnerabilities catalog (added 2022-03-03), indicating it is being actively exploited. 4 public proof-of-concept repositories are indexed.