EUVD-2026-44232
GHSA-4v4x-hh7w-55p3
Severity by source
AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
File-based client exploit: local vector and required user interaction to open the crafted spreadsheet, no privileges needed, full code-execution impact in the user's 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 for Enterprise, Office LTSC 2021/2024, and their macOS counterparts) arises from a heap-based buffer overflow (CWE-122) triggered when a victim opens a maliciously crafted spreadsheet. An unauthorized attacker can achieve arbitrary code execution in the context of the current user, gaining high confidentiality, integrity, and availability impact. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | Exploitation requires the victim to open an attacker-crafted Excel spreadsheet file in a vulnerable Office build (UI:R user interaction is mandatory per the CVSS vector), on any of the affected Windows or macOS Office SKUs. … 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 - a local attack vector requiring user interaction (opening a crafted file) but no prior authentication or privileges, yielding full impact within the user's context. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | An attacker emails or shares a specially crafted Excel spreadsheet - for example as a phishing attachment or a link to a document - and a user opens it in a vulnerable Office/Excel build. Excel's parser overflows a heap buffer while processing the malformed content, allowing the attacker's shellcode to run with the victim user's privileges. … |
| Remediation | Apply the Microsoft update for CVE-2026-56156 per the MSRC advisory at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-56156; patch status is Patch available per vendor advisory, though an exact fixed build number was not included in the input and should be taken from that advisory for each affected channel (Microsoft 365 Apps, Office LTSC 2021/2024, and the macOS equivalents). … Detailed patch versions, workarounds, and compensating controls in full report. |
Recommended ActionAI
Within 24 hours: Inventory all Microsoft Office Excel deployments (Microsoft 365 Apps for Enterprise, Office LTSC 2021/2024, and macOS equivalents) and advise users against opening spreadsheets from untrusted sources. …
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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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