EUVD-2026-43879
GHSA-hjhc-g9rv-g7cr
Severity by source
AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Local content-parsing bug needing no attacker privileges but requiring the victim to open the file, so AV:L/PR:N/UI:R with full C/I/A impact at user context.
Primary rating from Vendor (microsoft).
CVSS VectorVendor: microsoft
Lifecycle Timeline
2DescriptionCVE.org
Heap-based buffer overflow in Windows Data dll allows an unauthorized attacker to execute code locally.
AnalysisAI
Local code execution in Microsoft Windows arises from a heap-based buffer overflow in a Windows Data DLL, letting an attacker who can get a victim to open crafted content run arbitrary code with the victim's privileges. Affected builds span Windows 10 (1607 through 22H2), Windows 11 (24H2, 25H2, 26H1), and Windows Server 2012 through 2025. Microsoft (the reporter) has released a patch; there is no public exploit identified at time of analysis and it is not listed in CISA KEV.
Technical ContextAI
The flaw is a CWE-122 heap-based buffer overflow in a Microsoft Windows 'Data' DLL - a shared library that parses or handles structured data on behalf of applications. Heap overflows occur when input is copied into a heap-allocated buffer without adequate bounds checking, corrupting adjacent heap metadata or object pointers; a skilled attacker can groom the heap to convert this corruption into control-flow hijack and arbitrary code execution. The CPE set identifies the affected code as shipping across the modern Windows client and server line (Windows 10 1607/1809/21H2/22H2, Windows 11 24H2/25H2/26H1, and Windows Server 2012/2012 R2/2016/2019/2022/2025, including Server Core installations), indicating the vulnerable DLL is a core OS component rather than an optional feature.
RemediationAI
Patch available per vendor advisory: apply the Microsoft security update for CVE-2026-50347 via Windows Update or WSUS/MSRC for every affected client and server SKU, consulting the MSRC Update Guide at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-50347 for the exact KB and build numbers per platform (no single fixed version string was provided in the input, so obtain the precise KB from MSRC). Prioritize deployment on multi-user and RDP/terminal servers and on endpoints where users routinely open untrusted files, since exploitation depends on user interaction. Until patches are applied, reduce risk by restricting the opening of untrusted files and content that route through the affected data-handling component, enforcing least-privilege user accounts (so successful exploitation yields non-admin rather than SYSTEM-level access), and enabling attack-surface-reduction and exploit-mitigation controls (e.g., Microsoft Defender ASR rules and application allow-listing); note these are compensating controls that reduce likelihood, not a substitute for the update, and may block some legitimate file workflows.
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Same weakness CWE-122 – Heap-based Buffer Overflow
View allSame technique Heap Overflow
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External POC / Exploit Code
Leaving vuln.today