CVE-2009-3129
CVE-2009-3129 is a security flaw in Microsoft Excel, part of Microsoft Office. Attackers can run their own code on Microsoft Excel. The US Cybersecurity and Infrastructure Security Agency (CISA) added it to its catalog of flaws known to be used in attacks on 3 Mar 2022.[1]
Microsoft Excel is in things households have, such as phones, computers, browsers and everyday apps, so the fix matters at home as much as at work. Microsoft has published a fix or advice.
Description
CISA calls it a featheader record memory corruption in Microsoft Excel. In its words: “Microsoft Office Excel 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.”[1]
The CVE record adds: “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."”[2]
The underlying weakness is code injection (CWE-94), in MITRE’s list of common software weaknesses.
It scores 7.8 out of 10 on the Common Vulnerability Scoring System, which rates it high, scored by NVD using CVSS 3.1.[2]
Affected versions
NVD’s record doesn’t list version ranges for it; Microsoft’s advisory has them[3]. CISA names the product as Microsoft Excel.
Every device with Microsoft Excel needs the update.
Exploitation
CISA added it to its catalog of known exploited vulnerabilities on 3 Mar 2022, 4,495 days after it was made public. CISA lists a flaw only when it has reliable evidence of it being exploited, and gave US federal agencies until 24 Mar 2022 to fix it.[1]
FIRST’s Exploit Prediction Scoring System, which estimates how likely a flaw is to be used in attacks in the next 30 days from what it sees across the internet, puts it at 84%. That’s in the top 1% of the flaws it scores.[4]
CISA assesses it as not automatable: each attack takes some work.
CISA doesn’t say who was attacked, or how.
Fix
Microsoft has published a fix or advice.[3] CISA’s required action: “Apply updates per vendor instructions.”[1]
- Update Microsoft Excel now.On Windows: Settings, Windows Update, Check for updates, then restart. Office updates come the same way, or from any Office app: File, Account, Update Options. Then turn on automatic updates, so the next fix arrives on its own.
- If there’s no update, stop using it.CISA’s advice when a flaw being used in attacks has no fix is to stop using the product until it does.
Timeline
| Date | Event |
|---|---|
| The flaw is made public in the National Vulnerability Database, with a severity score of 7.8.[2] | |
| CISA adds it to its catalog of flaws known to be used in attacks.[1] | |
| CISA’s deadline for US government agencies to fix it.[1] | |
| FIRST puts the odds of it being used in attacks in the next 30 days at 84%.[4] |
See also
Other Microsoft Excel flaws
- CVE-2019-1297: remote code execution ·
- CVE-2016-7262: office security feature bypass ·
Other Microsoft flaws
- CVE-2026-96951, Microsoft Windows: command injection ·
- CVE-2026-65660, Microsoft SharePoint: code injection ·
- CVE-2026-85880, Microsoft Windows: heap-based buffer overflow ·
- CVE-2026-81963, Microsoft Windows: link following ·
- CVE-2019-1068, Microsoft SQL Server: remote code execution ·
Other code injection flaws
- CVE-2026-0322, Palo Alto Networks PAN-OS: code injection ·
- CVE-2026-60004, Gitea: code injection ·
- CVE-2026-72530, TrueConf Server: code injection ·
- CVE-2025-62593, Ray-Project Ray: code injection ·
- CVE-2026-9198, IBM Langflow: code injection ·
Added the same day
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- CVE-2022-20703, Cisco Small Business RV160, RV260, RV340, and RV345 Series Routers: small business RV series routers stack-based buffer overflow ·
- CVE-2022-20701, Cisco Small Business RV160, RV260, RV340, and RV345 Series Routers: small business RV series routers stack-based buffer overflow ·
- CVE-2022-20700, Cisco Small Business RV160, RV260, RV340, and RV345 Series Routers: small business RV series routers stack-based buffer overflow ·
- CVE-2022-20699, Cisco Small Business RV160, RV260, RV340, and RV345 Series Routers: small business RV series routers stack-based buffer overflow ·
Every Microsoft flaw on CISA’s list · Everything added in March 2022
References
- ^ Cybersecurity and Infrastructure Security Agency. “Microsoft Excel Featheader Record Memory Corruption Vulnerability”. Known Exploited Vulnerabilities Catalog, added 3 Mar 2022.
- ^ National Institute of Standards and Technology. “CVE-2009-3129 Detail”. National Vulnerability Database, published 11 Nov 2009.
- ^ Microsoft. Advisories and fixes: docs.microsoft.com.
- ^ FIRST. “Exploit Prediction Scoring System”. EPSS 0.840, percentile 99.7, 31 Oct 2026.
- CVE Program. “CVE-2009-3129”. The official CVE record.
This article is built from CISA’s catalog (version 2026.10.30), NVD’s record and FIRST’s scores, kept in HARD’s database and checked every morning. The plain English is HARD’s.