EUVD-2026-44202
GHSA-vh57-7369-46vq
Severity by source
AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
File-based local vector (AV:L) with no privileges but required user interaction to open the document (UI:R); memory-corruption code execution yields full C/I/A impact in the user context.
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 Office Excel (across Microsoft 365 Apps, Office 2016/2019, LTSC 2021/2024, Office for Mac, and Office Online Server) stems from a heap-based buffer overflow (CWE-122) that an attacker triggers when a victim opens a maliciously crafted spreadsheet. Rated CVSS 7.8 with no privileges required but mandatory user interaction, successful exploitation yields full confidentiality, integrity, and availability impact in the context of the victim user. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | Exploitation requires the victim to open an attacker-supplied malicious Excel file and, on Windows, to exit Protected View / enable editing - the CVSS vector confirms this with UI:R (user interaction required) and AV:L (local file-handling vector, not a remote network service). … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | The CVSS 3.1 vector (AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H, 7.8 High) describes a classic client-side document exploit: no attacker privileges are needed, but the victim must open the malicious file (UI:R), and the vector is Local because delivery relies on file handling rather than a network service. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | An attacker emails a target a crafted .xlsx/.xls spreadsheet disguised as an invoice or report; when the victim opens it in a vulnerable Excel build and dismisses Protected View, the malformed record triggers the heap overflow and runs attacker code in the user's security context. No credentials or elevated privileges are required beyond convincing the user to open and edit the file. … |
| Remediation | Apply the Microsoft security update for CVE-2026-55137; a patch is available from the vendor and the exact fixed build for each product/channel is published in the MSRC advisory at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-55137 (Patch available per vendor advisory - no single fixed version string was supplied in the input, so cite the per-channel build from the advisory rather than an invented number). … Detailed patch versions, workarounds, and compensating controls in full report. |
Recommended ActionAI
Within 24 hours, identify all systems running affected Office versions (Microsoft 365, Office 2016/2019, LTSC 2021/2024, Office for Mac, and Office Online Server) and issue security awareness communication instructing users to avoid opening spreadsheet files from untrusted sources; simultaneously, prepare patch deployment automation and test patches in non-production environments. …
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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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