EUVD-2026-56758
GHSA-pr9p-842j-v7hq
Severity by source
AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
File-parsing vulnerability triggered locally (AV:L); no privileges needed by attacker (PR:N); victim must open the file (UI:R); full code execution yields 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
3DescriptionCVE.org
Numeric truncation error 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 with full system impact when a victim opens a maliciously crafted workbook. The root cause is a numeric truncation error (CWE-122) in Excel's file parsing logic, where an integer value is truncated before being used to size a heap allocation, resulting in an undersized buffer that can be overflowed. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | The victim must actively open a crafted Excel file in Microsoft Excel on a local Windows system - this is the mandatory user interaction condition (UI:R in the CVSS vector). … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | The CVSS base score of 7.8 with a local attack vector accurately reflects the attack pattern: an attacker cannot exploit this remotely without first delivering a malicious file and inducing the victim to open it, which introduces a social engineering dependency and limits automated exploitation. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | An attacker crafts a malicious Excel workbook containing a specially structured record that triggers the numeric truncation error during file parsing, then delivers it to a target via phishing email or a compromised file-sharing link. When the victim opens the attachment in Microsoft Excel, the truncated size value causes a heap allocation that is too small for the incoming data, overflowing adjacent heap memory and redirecting execution to attacker-controlled code running as the victim user. … |
| Remediation | Apply the Microsoft security update addressing CVE-2026-68804 as published in the Microsoft Security Response Center advisory at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-68804. … Detailed patch versions, workarounds, and compensating controls in full report. |
Recommended ActionAI
Within 24 hours: Issue urgent security alert to users prohibiting opening Excel files from untrusted sources and configure email filtering for external Excel attachments. …
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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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