EUVD-2026-56711
GHSA-vf46-2j82-3mjw
Severity by source
AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Local file-based trigger (AV:L), user must open crafted document (UI:R), no attacker privileges needed (PR:N), full triad impact via 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
Integer underflow (wrap or wraparound) in Microsoft Office allows an unauthorized attacker to execute code locally.
AnalysisAI
Heap-based buffer overflow in Microsoft Office, rooted in an integer underflow during document parsing, enables local code execution with high confidentiality, integrity, and availability impact when a user opens a specially crafted file. All major Office release channels on both Windows and Mac are affected, including Microsoft 365 Apps for Enterprise, Office LTSC 2024/2021/2019/2016, and their Mac equivalents. …
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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 Office document - this is the sole gating condition (UI:R). … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | The CVSS 3.1 base score of 7.8 (High) with vector AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H reflects a realistic and well-calibrated assessment. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | An attacker crafts a malicious Office document (e.g., a Word .docx or Excel .xlsx file) that contains a specially structured data record designed to trigger the integer underflow in the Office parsing engine. The file is delivered to a target via a phishing email or compromised file share, and when the victim opens it, the integer underflow causes an undersized heap allocation, which is subsequently overflowed with attacker-controlled data, achieving arbitrary code execution in the context of the victim user. … |
| Remediation | The primary remediation is to apply the vendor-released patch via Microsoft Update or the Office deployment tooling. … Detailed patch versions, workarounds, and compensating controls in full report. |
Recommended ActionAI
Within 24 hours, identify all Microsoft Office deployments across the organization including Microsoft 365 Apps for Enterprise, Office LTSC 2024, 2021, 2019, and 2016 on Windows and Mac, and assess which systems are connected to patch management infrastructure. …
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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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