EUVD-2026-44167
GHSA-8v2q-jv8c-rv2h
Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain
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AccessCraft malicious Office document
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DeliveryDeliver via phishing or share
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ExploitVictim opens file
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ExecutionTrigger type confusion in parser
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ImpactExecute code as current user
Vulnerability Assessment
| Weakness |
CWE
ASVS 5.0
V15 - Secure Coding and Architecture Type safety enforcement
MITRE ATT&CK
1 technique across 1 tactic: Execution The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up. |
| Exploitation Conditions | Exploitation requires a local victim to open or preview an attacker-crafted Office document (UI:R - user interaction is mandatory), so this cannot be triggered remotely without user action and is not automatable. The CVSS vector shows PR:N (no attacker authentication needed) and AV:L (local vector, i.e., the malicious file must reach and be opened on the target host). Key limiting factors: the victim must actually open the file and, in practice, bypass Office Protected View / Mark-of-the-Web protections, and code runs only at the opening user's privilege level (S:U, no privilege escalation). Any of the affected Office builds on Windows or macOS in default configuration is susceptible once a crafted file is opened; no special non-default feature toggle is called out in the description. |
| Impact | The CVSS vector (AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H, 7.8 High) describes a low-complexity, unauthenticated-but-user-interaction-dependent local attack with high impact across C/I/A - a classic 'open a malicious document' client-side bug. Real-world risk hinges on social engineering: the local vector and UI:R requirement mean it is not wormable or remotely automatable, tempering urgency relative to a network-facing RCE, but Office file-format type-confusion bugs are historically attractive to phishing and targeted-attack operators. No EPSS score was provided, the CVE is absent from CISA KEV, and no POC is referenced, so there is no evidence of active or imminent mass exploitation at this time. The Microsoft-supplied 'Authentication Bypass' tag conflicts with the CWE-843 type-confusion classification and the code-execution description - treat that tag as unverified metadata rather than a confirmed second impact, and rely on the type-confusion/RCE characterization. |
| Exploit ScenarioDerived | An attacker crafts an Office document that triggers the type-confusion condition and delivers it via phishing email, a shared drive, or a download link; when the targeted user opens the file (and dismisses or bypasses Protected View), the malformed object is dereferenced as the wrong type and the attacker's payload executes with that user's privileges. No public exploit is identified at time of analysis, so this reflects the plausible path given the CVSS local vector with required user interaction rather than an observed campaign. |
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Alert meAnalysisAIv1 – Jul 14, 2026
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.
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.
Affected VersionsENISA
Affected Packages
Source: OSV (Open Source Vulnerabilities)
Affects your stack
Affects 4 packages in euvd
Checking this CVE against your own stacks and servers is part of the Basic plan and up.
Technical ContextAI · show details
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.
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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
DescriptionCVE.org
Access of resource using incompatible type ('type confusion') in Microsoft Office allows an unauthorized attacker to execute code locally.
Executive ViewAI
A type-confusion vulnerability in widely-deployed Microsoft Office products (2016 through 2024 versions and Microsoft 365 Apps) enables arbitrary code execution when users open crafted documents, directly affecting confidentiality, integrity, and availability across nearly every organization. The attack requires only user interaction-a normal business workflow of opening email attachments or shared files-with no special privileges or authentication needed. Immediate patch deployment is critical to prevent data theft, system compromise, or ransomware deployment before exploitation becomes widespread.
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Threat Intelligence Overview
NVD
CVE.org
EPSS
Vulnrichment
VulDB
How this decision was reached
The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.
What every action level means
SSVC AssessmentENISA
Priority Score
Attack Technique
Authentication bypass attacks exploit flaws in the verification mechanisms that control access to systems and applications.
Memory corruption occurs when a program writes data beyond the boundaries of allocated memory regions or accesses memory in unintended ways, violating the integrity of the process's address space.
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Exploit-DB