EUVD-2026-56695
GHSA-hr7x-mhcm-mj4v
Severity by source
AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
Local file-parsing flaw with no privileges needed, but mandatory user interaction; confidentiality-only impact with no integrity or availability effect.
Primary rating from Vendor (microsoft).
CVSS VectorVendor: microsoft
Lifecycle Timeline
3DescriptionCVE.org
Out-of-bounds read in Microsoft Office allows an unauthorized attacker to disclose information locally.
AnalysisAI
Out-of-bounds read (CWE-125) in Microsoft Office enables a local, unauthenticated attacker to disclose sensitive memory contents by convincing a user to open a specially crafted Office document. Affected products span the full modern Office portfolio - Office 2016 through Office LTSC 2024 and Microsoft 365 Apps for Enterprise. No public exploit code has been identified at time of analysis, and CISA SSVC rates exploitation as 'none' with non-automatable delivery, placing this in a lower operational urgency tier despite the High confidentiality impact rating.
Technical ContextAI
CWE-125 (Out-of-Bounds Read) describes a class of memory safety flaw where a program reads memory beyond the allocated buffer boundary, potentially exposing adjacent memory contents to the caller or an attacker-controlled output path. In the context of Microsoft Office document parsers - which process complex binary or XML-derived formats - an attacker-supplied crafted file can trigger this condition by providing malformed length fields, record counts, or offsets that cause the parser to read past a buffer's end. The CVSS vector (AV:L) confirms the attack surface is local file parsing rather than a network-facing component. Affected CPE covers Microsoft Office 2016 (16.0.0 through 16.0.5565.1001), Office 2019 (19.0.0+), Office LTSC 2021 (16.0.1+), Office LTSC 2024 (16.0.0+), and Microsoft 365 Apps for Enterprise (16.0.1+), as confirmed by EUVD-2026-56695.
RemediationAI
Apply the vendor-released patch via Microsoft Update or the Microsoft 365 admin center. For Microsoft Office 2016, the confirmed fixed build is 16.0.5565.1001; for all other affected product lines (Office 2019, LTSC 2021, LTSC 2024, Microsoft 365 Apps for Enterprise), consult the Office Security Releases page at https://aka.ms/OfficeSecurityReleases for the current patched build number per channel. The MSRC advisory at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-63529 provides authoritative patch guidance. As a compensating control where immediate patching is not feasible, consider restricting the opening of Office documents from untrusted or external sources using Protected View policies via Group Policy (enabling 'Open files from the internet in Protected View' and 'Open files in unsafe locations in Protected View'), which limits the parser's execution context and reduces the practical risk of this local file-parsing flaw. Note that Protected View restricts editing functionality, which may affect user workflows.
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Same weakness CWE-125 – Out-of-bounds Read
View allSame technique Buffer Overflow
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External POC / Exploit Code
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