EUVD-2026-56756
GHSA-cff6-wjc9-gpcj
Severity by source
AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
AV:L and UI:R reflect file-open trigger; PR:N because attacker controls only the delivered document; full CIA for arbitrary local code execution.
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
3DescriptionCVE.org
Heap-based buffer overflow in Microsoft Office Excel allows an unauthorized attacker to execute code locally.
AnalysisAI
Heap-based buffer overflow in Microsoft Office Excel enables local code execution when a victim opens a specially crafted workbook, resulting in full compromise of confidentiality, integrity, and availability on the local system. The CVSS 3.1 vector (AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H) confirms no attacker privileges are required, though user interaction - opening the malicious file - is a hard prerequisite. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | Exploitation requires the victim to actively open a specially crafted Microsoft Excel workbook on a system running a vulnerable version of Microsoft Office Excel - this is the mandatory user interaction (UI:R) condition without which the overflow cannot be triggered. … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | The CVSS 7.8 score and AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H vector accurately characterize a high-severity local code execution path: attack complexity is low once the malicious file is delivered, and no system privileges are required, making the social-engineering delivery layer the primary barrier. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | An attacker crafts a malicious Excel workbook embedding a heap overflow payload and delivers it to the target via a spearphishing email attachment or a compromised file-sharing link. When the victim opens the workbook in a vulnerable version of Excel, the parser triggers the heap overflow, corrupting heap structures to redirect execution to attacker-controlled shellcode that runs in the context of the victim user account. … |
| Remediation | Apply the Microsoft security update for Office Excel published via the MSRC update guide at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-68801; no exact fixed version number was present in the available intelligence, so the advisory must be consulted directly to identify the required update package and confirm applicability to your Office version. … Detailed patch versions, workarounds, and compensating controls in full report. |
Recommended ActionAI
Within 24 hours: Audit Excel deployment scope across the organization and communicate to users to avoid opening spreadsheets from untrusted sources; disable VBA macro execution where operationally feasible. …
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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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