EUVD-2026-35664
GHSA-cx48-vhm5-22rm
Severity by source
AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
Primary rating from Vendor (microsoft).
CVSS VectorVendor: microsoft
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
Lifecycle Timeline
3DescriptionCVE.org
Out-of-bounds read in Microsoft Office allows an unauthorized attacker to disclose information locally.
AnalysisAI
Out-of-bounds read in Microsoft Office triggers local information disclosure when a victim opens a crafted document, exposing adjacent memory contents with high confidentiality impact. The vulnerability spans a wide product surface including Office 2016 through LTSC 2024, Microsoft 365 Apps for Enterprise, multiple SharePoint Server versions, and Mac variants, as confirmed by EUVD-2026-35664. No public exploit or CISA KEV listing is identified at time of analysis; vendor-released patches are available across affected product lines.
Technical ContextAI
CWE-125 (Out-of-bounds Read) describes a condition where a read operation extends beyond the bounds of an allocated memory buffer, potentially exposing contents of adjacent memory regions to the calling context. In Microsoft Office's document parsing pipeline, a specially crafted file can trigger this condition, causing the application to read beyond its allocated buffer and surface memory data that may include sensitive runtime artifacts. The local attack vector (AV:L) in the CVSS vector indicates exploitation is tied to the local execution environment - specifically, opening a malicious Office document. CPE and EUVD data identify affected products across Windows (Office 2016, 2019, LTSC 2021, LTSC 2024, Microsoft 365 Apps for Enterprise, SharePoint Server 2016/2019/Subscription Edition) and macOS (Office 365 for Mac, LTSC for Mac 2021/2024). A notable discrepancy exists: the vulnerability tags include 'Buffer Overflow,' but the formally assigned CWE-125 identifies an out-of-bounds read - a distinct class from a write overflow; security teams should verify with the MSRC advisory for the precise memory operation involved.
RemediationAI
Apply vendor-released patches per the Microsoft Security Response Center advisory at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-44821. Specific patched build numbers confirmed via EUVD data: Office 2016 and SharePoint Enterprise Server 2016 require upgrade to 16.0.5556.1005 or later; SharePoint Server Subscription Edition requires 16.0.19725.20384 or later; SharePoint Server 2019 requires 16.0.10417.20153 or later. For Microsoft 365 Apps for Enterprise, Office 2019, Office LTSC 2021, Office LTSC 2024 (Windows and Mac), and Office 365 for Mac, exact patched build numbers were not enumerated in available data - consult https://aka.ms/OfficeSecurityReleases for current fix versions and apply the latest update. As a compensating control prior to patching, enforce Protected View for documents received from external or untrusted sources, which can prevent automatic triggering of parser code on untrusted files; note this may reduce usability for workflows involving external document collaboration. Additionally, Attack Surface Reduction (ASR) rules in Microsoft Defender can restrict Office document execution vectors, though coverage varies by file type. These controls do not eliminate the vulnerability and should be treated as temporary mitigations only.
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Same weakness CWE-125 – Out-of-bounds Read
View allSame technique Information Disclosure
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External POC / Exploit Code
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