What is the CVSS score of EUVD-2026-44209?

EUVD-2026-44209 has a CVSS 3.1 base score of 7.8 (High). CVSS vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H. EPSS exploitation probability: 0.3%.

Which versions of Microsoft Office Word are affected by EUVD-2026-44209?

CVE-2026-55134 affects Microsoft Word across Office 365, Office 2019/LTSC 2021/2024, Word 2016, and macOS deployments, enabling unauthenticated attackers to execute arbitrary code when users open…. A patch is available.

How to fix or mitigate EUVD-2026-44209?

Within 24 hours, inventory all affected Microsoft Office installations (Office 365, Office 2019, LTSC 2021, 2024, Word 2016, macOS) and test the vendor-released patch in a controlled environment. Within 7 days, begin staged deployment prioritizing power users and roles handling external documents, and reinforce email filtering rules to detect suspicious attachments. Within 30 days, complete full organizational patch deployment, verify compliance through patch management systems, and conduct user awareness training on document-based attack vectors.

Microsoft Office Word EUVD-2026-44209

| CVE-2026-55134 HIGH

Stack-based Buffer Overflow (CWE-121)

2026-07-14 microsoft

GHSA-29qv-mf54-6cq7

Buffer Overflow Microsoft Stack Overflow Microsoft Sharepoint Enterprise Server 2016 Microsoft Sharepoint Server 2019 Microsoft Sharepoint Server Subscription Edition Microsoft 365 Apps For Enterprise Microsoft Office Ltsc 2024 Microsoft Office 2019 Microsoft Office Ltsc 2021 Microsoft Office Ltsc For Mac 2021 Microsoft Office Ltsc For Mac 2024 Microsoft Word 2016 Microsoft Office 365 For Mac

7.8

CVSS 3.1 · Vendor: microsoft

Severity by source

Vendor (microsoft) PRIMARY

7.8 HIGH

AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

ENISA EUVD

CRITICAL

qualitative

vuln.today AI

7.8 HIGH

Local crafted-file vector with mandatory user interaction (AV:L/UI:R), no attacker auth (PR:N), and full RCE-level impact in the user context (C/I/A:H).

3.1 AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

4.0 AV:L/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

Primary rating from Vendor (microsoft).

CVSS VectorVendor: microsoft

Attack Vector

Local

Attack Complexity

Low

Privileges Required

None

User Interaction

Required

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Lifecycle Timeline

Analysis Generated

Jul 14, 2026 - 19:15 vuln.today

CVE Published

Jul 14, 2026 - 17:08 nvd

HIGH 7.8

DescriptionCVE.org

Stack-based buffer overflow in Microsoft Office Word allows an unauthorized attacker to execute code locally.

AnalysisAI

Local code execution in Microsoft Office Word (Microsoft 365 Apps, Office 2019/LTSC 2021/2024, Word 2016, and the macOS builds) arises from a stack-based buffer overflow triggered when a victim opens a maliciously crafted document. The CVSS 3.1 vector (AV:L/AC:L/PR:N/UI:R) shows an unauthenticated attacker needs no privileges but does require user interaction, and successful exploitation yields full confidentiality, integrity, and availability impact in the user's security context. There is no public exploit identified at time of analysis and it is not listed in CISA KEV, but Microsoft has released a patch.

Technical ContextAI

The flaw is a CWE-121 stack-based buffer overflow in Word's file-parsing code path. When Word processes a specially crafted document, it copies attacker-controlled data into a fixed-size stack buffer without adequate bounds checking, allowing corruption of the return address and adjacent stack variables to hijack control flow. Per the CPE data the vulnerable parsing component ships across the Office/Word family - Microsoft 365 Apps for Enterprise, Office 2019, Office LTSC 2021 and 2024, Word 2016, and the Office for Mac / Office LTSC for Mac 2021 and 2024 builds - and the same document-handling code is also surfaced through SharePoint Enterprise Server 2016, SharePoint Server 2019, and SharePoint Server Subscription Edition, which parse Office documents server-side. Because the overflow lives in shared Office rendering/parsing logic rather than a single binary, the affected surface spans both desktop clients and server products.

RemediationAI

Apply the Microsoft security update for CVE-2026-55134 as the primary fix - Patch available per vendor advisory - using the guidance and per-product build numbers published at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-55134 (exact fixed versions were not provided in the input data and should be taken directly from MSRC). Ensure Click-to-Run channels for Microsoft 365 Apps and the LTSC/perpetual and macOS builds are all updated, and patch the SharePoint servers as well. Until patched, reduce exposure by opening untrusted documents in Protected View / Application Guard and keeping macros disabled (side effect: users must explicitly trust files to edit them), blocking or quarantining Word documents from external email and web sources at the mail/proxy gateway (side effect: may delay legitimate documents), and restricting SharePoint document-processing endpoints to trusted users (side effect: reduced collaboration reach). These are compensating controls only and do not remove the underlying overflow.