EUVD-2026-56720
GHSA-h3x5-jw7p-ff7v
Severity by source
Sources disagree (Medium–Critical)AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
Local vector confirmed by document-open delivery mechanism; mandatory user interaction (UI:R); read-only memory disclosure maps to C:H with no integrity or availability impact.
vuln.today treats the vendor’s rating as authoritative. A higher third-party CVSS (e.g. CISA-ADP) is shown for transparency but does not drive the headline severity.
CVSS VectorVendor: microsoft
Lifecycle Timeline
3DescriptionCVE.org
Out-of-bounds read in Microsoft Office Word allows an unauthorized attacker to disclose information locally.
AnalysisAI
Out-of-bounds read in Microsoft Word's document parsing engine exposes sensitive in-process memory to a local attacker across Office 2016 through LTSC 2024 and macOS variants. Exploitation requires a victim to open a specially crafted document, making social engineering or phishing the primary delivery mechanism. No public exploit code exists and no active exploitation has been identified (not in CISA KEV); SSVC assessment rates exploitation status as none and technical impact as only partial.
Technical ContextAI
The root cause is CWE-125 (Out-of-bounds Read), a class of flaw in which a parser reads memory beyond the intended buffer boundary due to insufficient validation of field lengths or structural sizes within the parsed file format. Despite the 'Buffer Overflow' tag in the source intelligence - likely a legacy tagging artifact - the authoritative CWE designation is a read primitive, not a write primitive, meaning this flaw enables information disclosure rather than code execution. Affected products span both Windows and macOS builds: Microsoft Word 2016 (build < 16.0.5565.1000), Office 2019, LTSC 2021, LTSC 2024, and Microsoft 365 Apps for Enterprise on Windows (all builds prior to the August 2026 OfficeSecurityReleases update), as well as Office 365 for Mac, Office LTSC for Mac 2021, and LTSC for Mac 2024 (all builds prior to 16.112.26081010). The flaw is triggered during document parsing, implicating Word's core file format processing code shared across these product lines.
RemediationAI
Apply Microsoft's August 2026 security updates through Microsoft Update (Windows) or Microsoft AutoUpdate (macOS). For Microsoft Word 2016 on Windows, update to build 16.0.5565.1000 or later. For all macOS variants (Office 365 for Mac, LTSC for Mac 2021, LTSC for Mac 2024), update to build 16.112.26081010 or later. For Office 2019, LTSC 2021, LTSC 2024, and Microsoft 365 Apps for Enterprise on Windows, apply the current release from https://aka.ms/OfficeSecurityReleases - exact build numbers for these editions are not independently enumerated in available data. Where immediate patching is operationally blocked, enabling Protected View for documents from external sources (File > Options > Trust Center > Protected View) reduces exposure by opening untrusted files in a sandboxed read-only mode before full parsing occurs; note that this may disrupt workflows relying on active content or macros. Full advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-64917.
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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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