EUVD-2026-44230
GHSA-px56-54pw-c679
Severity by source
AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Client-side file-open memory corruption: local delivery (AV:L) requiring the victim to open a crafted file (UI:R), no prior privileges (PR:N), yielding full code execution in the user context (C:H/I:H/A:H).
Primary rating from Vendor (microsoft).
CVSS VectorVendor: microsoft
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Lifecycle Timeline
2DescriptionCVE.org
Heap-based buffer overflow in Microsoft Office Excel allows an unauthorized attacker to execute code locally.
AnalysisAI
Local code execution in Microsoft Excel (Office 2016 through Office LTSC 2024, Microsoft 365 Apps, Office for Mac, and Office Online Server) allows an attacker to run arbitrary code when a victim opens a maliciously crafted spreadsheet. The flaw is a heap-based buffer overflow (CWE-122) triggered during file parsing, giving full confidentiality, integrity, and availability impact in the user's context. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | Exploitation requires a victim to open an attacker-crafted Excel file in a vulnerable build - the CVSS vector's UI:R confirms mandatory user interaction, which is the primary limiting factor. … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | The CVSS 3.1 base score is 7.8 (High) with vector AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | An attacker crafts a malicious Excel workbook whose internal records overflow a heap buffer during parsing and emails or shares it (e.g., as an invoice or report) with a target. When the victim opens the file in a vulnerable Excel build outside Protected View, the overflow executes attacker-supplied code in the user's context. … |
| Remediation | Patch available per vendor advisory: apply the Microsoft security update referenced in the MSRC Update Guide at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-55947, which lists the exact fixed build for each affected edition (Microsoft 365 Apps, Excel 2016, Office 2019, Office LTSC 2021/2024, Office for Mac builds, and Office Online Server); the input does not include a single universal version number because fixes ship per-channel, so consult the advisory for your specific channel and install via Microsoft Update, Click-to-Run auto-update, or WSUS/Intune. … Detailed patch versions, workarounds, and compensating controls in full report. |
Recommended ActionAI
Within 24 hours: Identify all users running affected Office versions (Office 2016, 2019, LTSC 2024, Microsoft 365 Apps, Mac, and Online Server instances) and issue guidance prohibiting opening spreadsheets from untrusted sources. …
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Local code execution in Microsoft Office (including Microsoft 365 Apps for Enterprise, Office 2016/2019, and Office LTSC
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Arbitrary code execution in Microsoft PowerPoint (and the broader Microsoft Office/365 suite on Windows and macOS) arise
Local code execution in Microsoft Office PowerPoint (including Microsoft 365 Apps, Office 2019, Office LTSC 2021/2024, a
Local code execution in Microsoft Office PowerPoint (CWE-122 heap-based buffer overflow) lets an unauthorized attacker r
Local code execution in Microsoft Word (and the wider Microsoft Office / Microsoft 365 Apps family) lets an unauthorized
Local code execution in Microsoft Office (2016, 2019, LTSC 2021/2024, Microsoft 365 Apps for Enterprise, and Office for
Local code execution in Microsoft Office (2016, 2019, LTSC 2021/2024, Microsoft 365 Apps, and Office for Mac 2021/2024)
Same weakness CWE-122 – Heap-based Buffer Overflow
View allSame technique Heap Overflow
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External POC / Exploit Code
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