What is the CVSS score of CVE-2009-3129?

CVE-2009-3129 has a CVSS 3.1 base score of 7.8 (High). CVSS vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H. EPSS exploitation probability: 91.6%.

Is there a public PoC exploit available for CVE-2009-3129?

Yes, a public proof-of-concept exploit is available for CVE-2009-3129. Prioritise patching immediately. EPSS: 91.6%.

How to fix or mitigate CVE-2009-3129?

Within 24 hours: Identify all affected systems and apply vendor patches immediately. If patching is delayed, consider network segmentation to limit exposure.

Microsoft CVE-2009-3129

HIGH

Out-of-bounds Write (CWE-787)

2009-11-11 secure@microsoft.com

RCE Buffer Overflow Memory Corruption Microsoft

7.8

CVSS 3.1 · NVD

View

Vulnerability Assessment

Weakness	CWE CWE-787 OWASP Top 10:2025 A06:2021 - Vulnerable and Outdated Components ASVS 5.0 V14 - Configuration Dependency management, component inventory MITRE ATT&CK 2 techniques across 2 tactics: Execution, Privilege Escalation The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up. Sign in to read
Impact	High risk for legacy Office installations. Excel-based attacks were a primary APT delivery mechanism in 2009-2012. The vulnerability affects multiple Office versions including Mac editions and compatibility packs.
Exploit ScenarioDerived	An attacker sends a targeted email with a malicious .xls attachment to finance or HR personnel. Opening the spreadsheet in vulnerable Excel triggers the FEATHEADER overflow, installing a remote access trojan.

Act Now Prioritize within 24-48h. Why: In CISA KEV with patch available.

Exploited in the wild (CISA KEV) Patch available 91.6% exploitation probability (EPSS)

Get an e-mail when this CVE is exploited, patched or re-scored. Free account.

Alert me

AnalysisAIv1 – Mar 26, 2026

Microsoft Office Excel 2002 through 2007 and Office for Mac contain a memory corruption vulnerability triggered by a specially crafted spreadsheet with a malformed FEATHEADER record, allowing remote code execution.

Earlier versions of this analysis (1)

v1 Mar 26, 2026 - 11:17 CVSS 7.8

An out-of-bounds write vulnerability in Microsoft Excel's BIFF file format parser allows remote code execution when processing a spreadsheet containing a malformed FEATHEADER record structure.

RemediationAI

Apply Microsoft security update MS09-067. Migrate to current Office versions with Protected View and ASLR mitigations. Block legacy .xls formats at the email gateway.

Affects your stack

Find out whether the stacks and servers you run are on an affected version.

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

The CWE-787 flaw occurs when Excel parses the FEATHEADER record in legacy BIFF format files. A crafted record with incorrect size fields causes a heap-based buffer overflow, enabling arbitrary code execution in the context of the user running Excel.

Know when the next one hits your stack

Watch products and get an email when something new is published
Check this CVE against your own stack and servers
Exploit and PoC references, threat intelligence from 22 sources

Continue with Google Continue with GitHub

No credit card · 7-day full trial

Severity by source

NVD PRIMARY 7.8 HIGH

AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

Attack Vector

Local

Attack Complexity

Low

Privileges Required

None

User Interaction

Required

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Lifecycle Timeline

Added to CISA KEV

Oct 22, 2025 - 01:15 cisa

CISA KEV

PoC Detected

Oct 22, 2025 - 01:15 vuln.today

Public exploit code

Patch released

Oct 22, 2025 - 01:15 nvd

Patch available

CVE Published

Nov 11, 2009 - 19:30 nvd

HIGH 7.8

DescriptionCVE.org

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."

Executive ViewAI

Why It Matters

CVE-2009-3129 presents notable security risk, a out-of-bounds write vulnerability rated CVSS 7.8. Exploitation could allow attackers to corrupt memory, crash the application, or potentially execute arbitrary code. This vulnerability is actively exploited in the wild (KEV-listed) and requires immediate remediation. A patch is available and should be applied as part of regular vulnerability management.

Business Impact: Severe

Compensating Controls

Apply vendor patch. If immediate patching is not feasible: (1) Enable ASLR and DEP where available; (2) Implement network segmentation; (3) Monitor for exploitation indicators.

Threat Intelligence Overview

Threat Score

9.3/10

Composite threat intelligence

EPSS Score

91.6%

Top 0% exploitable

Threat Intel

1 sources

Exploit

POC

Public exploit code exists

Data Quality

8 sources

Confidence: High

NVD

CVE.org

CISA KEV

EPSS POC (1) THREAT

Exploit-DB

VulDB

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue

Severity HIGH

CISA KEV Yes

Public POC Yes

EPSS 91.6%

Patch available Yes

Active threat Yes

Deciding rule

In CISA KEV with patch available

What every action level means

Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.

Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.

This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.

This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.

Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived

Out-of-Cycle

Exploitation· derived

Active

System Exposure· derived

Small

Automatable· derived

Human Impact

Very High

Priority Score

226

Low Medium High Critical

KEV: +50

EPSS: +92

CVSS: +39

PoC: +20

Weaponized: +15

Threat intel: +10

Gov advisory: 0

Attack Technique

Buffer Overflow HIGH

A buffer overflow occurs when a program writes more data to a memory buffer than it was allocated to hold, causing the excess data to spill into adjacent memory regions.

Memory Corruption HIGH

Memory corruption occurs when a program writes data beyond the boundaries of allocated memory regions or accesses memory in unintended ways, violating the integrity of the process's address space.

Remote Code Execution CRITICAL

Remote Code Execution represents the critical moment when an attacker successfully runs arbitrary code on a target system without physical access.