CVE-2009-3129 — Microsoft Excel Featheader Record Memory Corruption Vulnerability

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

CISA SSVC assessment CISA

Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

• Documented patch — docs.microsoft.com (NIST National Vulnerability Database)

CISA required action CISA

Apply updates per vendor instructions.

US federal deadline: Mar 24, 2022 — passed 1666 day(s) ago

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

1. Identify exposed assets running the affected vendor/product/version combinations (Microsoft Excel, Microsoft Excel Viewer, Microsoft Office…).
2. Treat as emergency remediation: the CVE is in CISA KEV (confirmed exploitation).
3. Apply the fixed version or the patch documented under Remediation.
4. Exploitation requires user interaction: tighten email/web filtering and warn affected users.
5. EPSS ahead of 100% of scored CVEs: prioritize it in the patch queue.
6. Search available logs for exploit probes matching the vulnerability class (memory corruption), errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-787 · Out-of-bounds Write

Other CVEs with this weakness →

CISA KEV details CISA

CISA lists a CVE once it has evidence of exploitation against real targets.

CISA records ransomware use only for campaigns it has confirmed, so “Unknown” means unrecorded, not ruled out. The deadline binds US federal agencies; for everyone else it is a reference date.

Public exploits, PoCs and detection templates

Public code that demonstrates or tests the flaw raises the odds of mass exploitation — and Nuclei templates help find vulnerable assets in your environment.

Warning: public PoCs are sometimes disguised malware. Use them only for authorized testing in an isolated environment. This portal does not host exploit code — it only points to the sources.

Threat actors exploiting this CVE MITRE ATT&CK

According to MITRE ATT&CK.

EPSS over time FIRST

Oct 13, 2026 → Oct 14, 2026 · 2 reading(s) · max 84.03%

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

• Local/physical vector: focus on endpoint telemetry (EDR) from affected hosts.
• Correlate service crashes/restarts with inbound traffic; repeated crashes may indicate attempts.
• Hunt retroactively in logs from before Mar 3, 2022 (KEV listing): exploitation may have started earlier.

Timeline

What happened to this CVE, newest first.

• 2026
• SSVC assessment updated
  Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
• Record published
  Oct 13, 2026
• Fix documented
  Oct 13, 2026 · NIST National Vulnerability Database
• Affected products added · microsoft/excel, microsoft/excel viewer, microsoft/office, microsoft/open xml file format converter
  Oct 13, 2026 · NIST National Vulnerability Database
• CVSS changed · 7.8
  Oct 13, 2026 · NIST National Vulnerability Database
• Source status changed · → Analyzed
  Oct 13, 2026 · NIST National Vulnerability Database
• Added to CISA KEV (detected)
  Oct 13, 2026 · CISA Known Exploited Vulnerabilities
• Record created in this database
  Oct 13, 2026 · CISA Known Exploited Vulnerabilities
• 2022
• Added to CISA KEV catalog
  Mar 2, 2022 · CISA
• 2009
• CVE published
  Nov 11, 2009 · microsoft

Source activity

Repeated readings are counted rather than listed.

• 2× References added · Oct 13, 2026 – Oct 13, 2026
• 1× Official description updated · Oct 13, 2026 – Oct 13, 2026

References

13 on the record

• docs.microsoft.com/en-us/security-updates/securitybulletins/2009/ms09-067
  Patch, Vendor Advisory, vendor-advisory, x_refsource_MS, NIST National Vulnerability Database
• www.cisa.gov/known-exploited-vulnerabilities-catalog
  US Government Resource, NIST National Vulnerability Database
• www.securityfocus.com/bid/36945
  Broken Link, Third Party Advisory, VDB Entry, vdb-entry, x_refsource_BID, NIST National Vulnerability Database
• archives.neohapsis.com/archives/bugtraq/2009-11/0080.html
  Broken Link, mailing-list, x_refsource_BUGTRAQ, NIST National Vulnerability Database
• www.us-cert.gov/cas/techalerts/TA09-314A.html
  Third Party Advisory, US Government Resource, third-party-advisory, x_refsource_CERT, NIST National Vulnerability Database
• labs.idefense.com/intelligence/vulnerabilities/display.php
  Broken Link, third-party-advisory, x_refsource_IDEFENSE, NIST National Vulnerability Database
• oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A6521
  Broken Link, vdb-entry, signature, x_refsource_OVAL, NIST National Vulnerability Database
• osvdb.org/59860
  Broken Link, vdb-entry, x_refsource_OSVDB, NIST National Vulnerability Database
• www.exploit-db.com/exploits/14706
  Exploit, Third Party Advisory, VDB Entry, exploit, x_refsource_EXPLOIT-DB, NIST National Vulnerability Database
• www.securitytracker.com/id
  Broken Link, Third Party Advisory, VDB Entry, vdb-entry, x_refsource_SECTRACK, NIST National Vulnerability Database
• nvd.nist.gov/vuln/detail/CVE-2009-3129
  GitHub Security Advisories
• www.zerodayinitiative.com/advisories/ZDI-09-083
  Third Party Advisory, VDB Entry, x_refsource_MISC, NIST National Vulnerability Database
• github.com/advisories/GHSA-8325-hmcc-g9mq
  GitHub Security Advisories

Elsewhere on this site

Related CVEs (same products)

• Medium CVE-2026-85875 Microsoft Office Excel Information Disclosure Vulnerability Sep 8, 2026
• High CVE-2026-81957 Microsoft Excel Remote Code Execution Vulnerability Sep 8, 2026
• High CVE-2026-81956 Microsoft Excel Remote Code Execution Vulnerability Sep 8, 2026
• Medium CVE-2026-81958 Microsoft Excel Information Disclosure Vulnerability Sep 8, 2026
• High CVE-2026-81960 Microsoft Excel Remote Code Execution Vulnerability Sep 8, 2026
• High CVE-2026-81959 Microsoft Excel Remote Code Execution Vulnerability Sep 8, 2026

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

• No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
• No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
• No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2009-3129 is "Microsoft Excel Featheader Record Memory Corruption Vulnerability", rated High. It affects Excel (Microsoft); versions are in the scope table. It is in CISA KEV: there is evidence of real-world exploitation. CVSS 7.8 describes technical severity. EPSS 84.03% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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