EUVD-2026-73866
GHSA-4469-59cq-475f
Severity by source
AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
File-based exploit requires local execution and user interaction with no host privileges; full C/I/A compromise consistent with memory-corruption-to-code-execution chain.
Primary rating from Vendor (microsoft).
CVSS VectorVendor: microsoft
Lifecycle Timeline
4DescriptionCVE.org
Out-of-bounds read in Microsoft Office Excel allows an unauthorized attacker to execute code locally.
AnalysisAI
Out-of-bounds read (CWE-125) in Microsoft Office Excel's file-parsing engine enables local code execution when a victim opens a specially crafted spreadsheet. Affects a wide range of Microsoft Office products from version 2016 through LTSC 2024 and Microsoft 365 Apps for Enterprise, on both Windows and Mac platforms. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | Exploitation requires a victim user to open a specially crafted Excel spreadsheet file (UI:R), which is the primary limiting condition. … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | The CVSS 7.8 vector (AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H) characterizes this as a file-triggered, user-interaction-required exploit with full system compromise potential and no privilege prerequisites. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | Full exploit scenario with step-by-step reproduction available after sign-in. |
| Remediation | Microsoft has released patches for all confirmed affected products; apply the fixed builds per EUVD-2026-73866: upgrade Office 2016 and Excel 2016 to 16.0.5569.1003 or later, Office 2019 and Office Online Server to 16.0.10417.20207 or later, Office LTSC 2021 to 16.0.14334.20896 or later, Office LTSC 2024 to 16.0.17932.20960 or later, and Microsoft 365 Apps for Enterprise to 16.0.20326.20138 or later. … Detailed patch versions, workarounds, and compensating controls in full report. |
Recommended ActionAI
Within 24 hours, inventory all deployments of Microsoft Office Excel across Windows and Mac (Office 2016 through LTSC 2024 and Microsoft 365 Apps for Enterprise) and alert users to exercise caution when opening unexpected spreadsheet attachments. …
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Same weakness CWE-125 – Out-of-bounds Read
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External POC / Exploit Code
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