Office
CVE-2026-26109
HIGH
Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain
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AccessCraft malicious Excel file with out-of-bounds pointer
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ExploitUser opens file locally
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ExecutionOut-of-bounds read triggers memory disclosure
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ImpactExecute arbitrary code with user privileges
Vulnerability Assessment
| Weakness |
CWE
OWASP Top 10:2025
A06:2021 - Vulnerable and Outdated Components
ASVS 5.0
V15 - Secure Coding and Architecture Bounds checking, read limits
MITRE ATT&CK
1 technique across 1 tactic: Collection The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up. |
| Exploitation Conditions | Local file access required. Attacker must convince user to open malicious .xlsx/.xls file. No authentication needed. Exploits Excel's parsing of crafted worksheet structures causing out-of-bounds memory read. |
| Impact | CVSS 8.4 (HIGH). Attack vector: Local. Complexity: Low. Privileges required: None. User interaction: None. Exploitation no authentication required. Exploitable via local access. |
| Exploit ScenarioDerived | An attacker without authentication could exploit this vulnerability to compromise the affected system. |
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Alert meAnalysisAIv1 – Mar 12, 2026
Arbitrary code execution in Microsoft Office Excel and related products (Office Online Server, 365 Apps) via out-of-bounds memory read allows local attackers to achieve complete system compromise without requiring user interaction or elevated privileges. This high-severity vulnerability affects multiple Microsoft Office components and currently lacks a security patch. An attacker with local access can exploit memory corruption to execute malicious code with full system permissions.
Earlier versions of this analysis (1)
Out-of-bounds read in Microsoft Office Excel allows an unauthorized attacker to execute code locally. [CVSS 8.4 HIGH]
RemediationAI
Monitor vendor advisories for a patch.
Affected Packages
Source: OSV (Open Source Vulnerabilities)
Affects your stack
Affects 9 packages in microsoft
Checking this CVE against your own stacks and servers is part of the Basic plan and up.
Technical ContextAI · show details
Classified as CWE-125 (Out-of-bounds Read). Out-of-bounds read in Microsoft Office Excel allows an unauthorized attacker to execute code locally.
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- Exploit and PoC references, threat intelligence from 22 sources
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Severity by source
AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Primary rating from NVD · only source for this CVE.
CVSS VectorNVD
DescriptionCVE.org
Out-of-bounds read in Microsoft Office Excel allows an unauthorized attacker to execute code locally.
Executive ViewAI
CVE-2026-26109 is a critical vulnerability in Microsoft Office Excel that allows attackers to execute malicious code on affected systems through specially crafted spreadsheet files. This poses an immediate risk to any organization where employees use Excel, potentially compromising sensitive data, intellectual property, and system integrity across the enterprise.
Disable Excel macro execution for all users except those with documented business need; implement application whitelisting to restrict Excel process execution scope; configure email gateway rules to block or quarantine Excel files from external sources; apply the principle of least privilege to file access permissions; monitor for suspicious Excel process behavior; consider disabling OLE embedding features; segregate high-risk users or departments to isolated network segments; maintain offline backups of critical Excel files.
Threat Intelligence Overview
NVD
CVE.org
EPSS
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.
What every action level means
SSVC AssessmentENISA
Priority Score
Attack Technique
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.
Information disclosure occurs when an application unintentionally exposes sensitive data that aids attackers in reconnaissance or directly compromises security.
Affected Products (CPE)CVE.org
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GitHub PoC
Exploit-DB