EUVD-2026-29648
GHSA-gw2g-hq8h-6fvx
Severity by source
AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Local document-open UAF: AV:L and UI:R because the victim must open a crafted file; PR:N as no prior auth is needed; full C/I/A impact at unchanged user scope.
Primary rating from NVD.
CVSS VectorNVD
Lifecycle Timeline
2DescriptionCVE.org
Use after free in Microsoft Office Word allows an unauthorized attacker to execute code locally.
Articles & Coverage 1
AnalysisAI
Local code execution in Microsoft Word (and the Office suites that bundle it - Office 2016/2019, LTSC 2021/2024, Microsoft 365 Apps, and Office LTSC for Mac 2021/2024) stems from a use-after-free memory-corruption defect that lets an attacker run arbitrary code in the context of the current user, typically by having the victim process a crafted document. Microsoft (the reporting party) has released a fix; there is no public exploit identified at time of analysis and EPSS is very low (0.04%, 14th percentile). SSVC rates exploitation as none but technical impact as total, so this is a patch-on-schedule item rather than an emergency.
Technical ContextAI
The flaw is a CWE-416 use-after-free in Microsoft Word's document-processing engine, the shared parsing/rendering code reused across the Office family. A use-after-free occurs when memory is freed but a dangling pointer is later dereferenced; an attacker who controls document structure can groom the heap so the freed object is replaced with attacker-controlled data, converting the dangling reference into a controlled read/write and ultimately code execution. The CPE set confirms the affected code ships in cpe:2.3:a:microsoft:microsoft_word_2016, microsoft_office_2019, microsoft_office_ltsc_2021, microsoft_office_ltsc_2024, microsoft_365_apps_for_enterprise, and the two Office LTSC for Mac (2021, 2024) editions, indicating the vulnerable component is common to both Windows and macOS Word builds. The 'Denial Of Service' and 'Memory Corruption' tags reflect that the same corruption can also crash the process.
RemediationAI
Vendor-released patch: apply the Microsoft security update referenced at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-40366 - for Microsoft Word 2016 update to build 16.0.5552.1000 or later, and for Office LTSC for Mac 2021/2024 update to 16.109.26051019 or later; Microsoft 365 Apps, Office 2019, and Office LTSC 2021/2024 receive the fix through their respective Office update channels (Click-to-Run / Windows Update / Microsoft Update). Until patches are deployed, reduce exposure by opening untrusted documents in Protected View and keeping it enabled for internet and Outlook attachments, blocking or sandboxing inbound Office documents at the mail gateway, and enabling Attack Surface Reduction rules that constrain Office child-process and memory behavior; note these controls can interrupt legitimate document workflows and macro-enabled business processes, so validate before broad enforcement. Track the advisory under ENISA EUVD-2026-29648.
Local code execution in Microsoft Word (and Office/SharePoint components that render Word content) stems from an integer
Arbitrary code execution in Microsoft Office Word (and the broader Office/365/SharePoint family) arises from a stack-bas
Local code execution in Microsoft Word (part of Microsoft 365 Apps, Office 2019, Office LTSC 2021/2024, and Office for M
Arbitrary code execution in Microsoft PowerPoint (and the broader Microsoft Office/365 suite on Windows and macOS) arise
Local code execution in Microsoft Office PowerPoint (including Microsoft 365 Apps, Office 2019, Office LTSC 2021/2024, a
Local code execution in Microsoft Office PowerPoint (CWE-122 heap-based buffer overflow) lets an unauthorized attacker r
Local code execution in Microsoft Word (and the wider Microsoft Office / Microsoft 365 Apps family) lets an unauthorized
Local code execution in Microsoft Word (Office 2016/2019, Microsoft 365 Apps, Office LTSC 2021/2024) arises from a heap-
Local code execution in Microsoft Office Word (CWE-416 use-after-free) allows an unauthorized attacker to run arbitrary
Local code execution in Microsoft Office Word (Microsoft 365 Apps, Office 2019/LTSC 2021/2024, Word 2016, and the macOS
Local code execution in Microsoft Office Word (via a stack-based buffer overflow, CWE-121) lets an attacker run arbitrar
Local code execution in Microsoft Office Word (across Microsoft 365 Apps, Office 2019/LTSC 2021/2024, Office for Mac, an
Same weakness CWE-416 – Use After Free
View allSame technique Denial Of Service
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External POC / Exploit Code
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