EUVD-2026-44167
GHSA-8v2q-jv8c-rv2h
Severity by source
AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Local file must be opened by the user (AV:L, UI:R) with no attacker auth (PR:N); type confusion yields full code execution as the user, so C/I/A all High and scope unchanged.
Primary rating from Vendor (microsoft).
CVSS VectorVendor: microsoft
Lifecycle Timeline
2DescriptionCVE.org
Access of resource using incompatible type ('type confusion') in Microsoft Office allows an unauthorized attacker to execute code locally.
AnalysisAI
Local arbitrary code execution in Microsoft Office (2016, 2019, LTSC 2021/2024, Microsoft 365 Apps for Enterprise, and Office for Mac 2021/2024) arises from a type-confusion flaw (CWE-843) that lets an attacker run code in the context of the current user when a victim opens a crafted file. The CVSS 3.1 base score is 7.8 (AV:L/AC:L/PR:N/UI:R) reflecting local vector with required user interaction and high impact to confidentiality, integrity, and availability. There is no public exploit identified at time of analysis and it is not listed in CISA KEV, but a vendor patch is available via MSRC.
Technical ContextAI
The root cause is CWE-843, access of a resource using an incompatible type ('type confusion'), a memory-corruption class in which code interprets a memory region as one object type while it actually holds another, allowing attacker-controlled data to be treated as a pointer, vtable, or length field and ultimately steering execution. In Office this typically occurs in the parsers and object models that deserialize rich document content (embedded objects, records, or structured storage) where a mismatched type is dereferenced. The CPE data confirms the affected code spans the shared Office parsing stack across Windows builds (Microsoft 365 Apps for Enterprise, Office 2016, Office 2019, Office LTSC 2021, Office LTSC 2024) and the macOS builds (Office 365/LTSC for Mac 2021 and 2024), indicating the vulnerable component is in cross-platform Office code rather than an OS-specific layer.
RemediationAI
Patch available per vendor advisory: apply the Microsoft security update for CVE-2026-55022 documented in the MSRC Update Guide at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-55022, which covers Windows Office (365 Apps for Enterprise, 2016, 2019, LTSC 2021, LTSC 2024) and the macOS builds (Office 365/LTSC for Mac 2021 and 2024); the exact fixed build numbers are listed on that page and should be pushed via Microsoft Update, Click-to-Run, or your patch-management system. Because exploitation requires a user to open a malicious file, effective compensating controls until patching completes include enforcing Protected View and blocking macros/content from the internet and email, using Office 'Block files from the Internet' / Mark-of-the-Web policies, and restricting or blocking risky embedded object and file types at the mail gateway - note these can disrupt legitimate document workflows and add user friction. Attack Surface Reduction rules that block Office from creating child processes or injecting code provide additional defense-in-depth with minimal side effects for most environments.
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 technique Memory Corruption
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External POC / Exploit Code
Leaving vuln.today