EUVD-2026-56691
GHSA-p392-rqwr-573j
Severity by source
AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Local document delivery requires user to open the file (UI:R, AV:L); opening Word requires no prior privilege (PR:N); full triad impact consistent with arbitrary code execution in user session.
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 Word allows an unauthorized attacker to execute code locally.
AnalysisAI
Code execution in Microsoft Word stems from a numeric truncation error (CWE-197) in the document processing engine, affecting Word 2016, Office 2019, LTSC 2021, LTSC 2024, and Microsoft 365 Apps for Enterprise. Exploitation requires a user to open a specially crafted document, after which an attacker can execute arbitrary code with full confidentiality, integrity, and availability impact under the victim's session. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | Exploitation requires the target user to actively open a specially crafted Word document on a system running an unpatched version of Microsoft Word 2016 (below 16.0.5565.1000), Office 2019, Office LTSC 2021, Office LTSC 2024, or Microsoft 365 Apps for Enterprise. … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | The CVSS 3.1 score of 7.8 (AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H) reflects the classic document-delivery exploitation model: local attack vector with no privilege requirement but mandatory user interaction. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | An attacker crafts a malicious Word document containing a specially structured record with a numeric field designed to trigger a truncation error in Word's parser. The document is delivered to a target user via a phishing email attachment or a file-sharing link; when the user opens it in an unpatched version of Microsoft Word, the truncation corrupts memory in a way that redirects execution to attacker-controlled code running under the user's session. … |
| Remediation | Apply the vendor-released patch immediately through Microsoft Update, the Microsoft Update Catalog, or your enterprise patch management tooling. … Detailed patch versions, workarounds, and compensating controls in full report. |
Recommended ActionAI
Within 24 hours: Issue security advisory to all employees warning against opening unsolicited Word documents, and identify all systems running affected Microsoft Office versions (Word 2016, Office 2019, LTSC 2021, LTSC 2024, Microsoft 365 Apps for Enterprise). …
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Same weakness CWE-197 – Numeric Truncation Error
View allSame technique Authentication Bypass
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External POC / Exploit Code
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