EUVD-2026-56764
GHSA-rhm8-v74c-45m2
Severity by source
AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Local trigger requiring only a standard user account, no user interaction, achieving full code execution - PR:L and AV:L are independently justified by CVSS vector and SSVC non-automatable finding.
Primary rating from Vendor (microsoft).
CVSS VectorNVD
Lifecycle Timeline
5DescriptionNVD
Heap-based buffer overflow in Microsoft Office allows an unauthorized attacker to execute code locally.
AnalysisAI
Heap-based buffer overflow in Microsoft Office (365 Apps for Enterprise, Office 2019, Office 2021 LTSC, and Office 2024 LTSC) enables a local attacker with low-privilege credentials to execute arbitrary code with the full confidentiality, integrity, and availability impact of the Office process. The vulnerability (CWE-122) carries a CVSS 3.1 score of 7.8 and requires only local access and a standard user account - no user interaction is needed once the attacker can trigger the vulnerable allocation path. No public exploit code has been identified at time of analysis, and SSVC assessment confirms current exploitation status as none.
Technical ContextAI
CWE-122 describes a heap-based buffer overflow, where an application writes data beyond the allocated bounds of a heap buffer. This class of flaw allows attackers to corrupt adjacent heap metadata or data structures - including function pointers or vtable entries - enabling control-flow hijacking and arbitrary code execution. The affected products, confirmed via CPE strings, span both x86 and x64 architectures across four Office product lines: Microsoft 365 Apps for Enterprise (starting at version 16.0.1), Office 2019 (starting at version 19.0.0), Office LTSC 2021 (starting at version 16.0.1), and Office LTSC 2024 (starting at version 16.0.0). The vulnerability is triggered locally within Office's processing logic, consistent with the AV:L CVSS metric. Reported by Microsoft's own security team (secure@microsoft.com) and tracked under ENISA EUVD-2026-56764.
RemediationAI
Patch available per vendor advisory - apply the latest cumulative Office update via Microsoft Update, Windows Update, or the Microsoft Update Catalog, referencing https://aka.ms/OfficeSecurityReleases for product-specific guidance. Exact patched version numbers beyond the affected lower bounds are not independently confirmed in available data; consult the MSRC advisory at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-70130 for the specific build numbers that resolve the issue. Organizations that cannot patch immediately should apply the principle of least privilege rigorously: ensure standard users cannot install software or write to Office executable directories, which reduces the ability of a low-privileged attacker to stage a supporting payload, though this does not eliminate the vulnerability itself. Monitoring for anomalous child process spawning from Office applications (e.g., Office spawning cmd.exe or PowerShell) via endpoint detection tooling can serve as a compensating detective control.
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Same weakness CWE-122 – Heap-based Buffer Overflow
View allSame technique Buffer Overflow
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External POC / Exploit Code
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