CVE-2026-69719: Microsoft 365 Apps Information Disclosure

CVE-2026-69719 Overview

CVE-2026-69719 is an information disclosure vulnerability in Microsoft Office Word caused by a buffer over-read [CWE-126]. An unauthorized attacker can read memory beyond an allocated buffer by tricking a user into opening a specially crafted document. The flaw affects multiple Office product lines, including Microsoft 365 Apps, Office 2019, Office 2021, Office 2024, and Word 2016 on both Windows and macOS. Exploitation requires user interaction but no authentication. Successful attacks expose sensitive process memory that may contain document contents, credentials, or other confidential data.

Critical Impact
Attackers can disclose sensitive memory contents from the Word process after a user opens a malicious document delivered by email, chat, or web download.

Affected Products

Microsoft 365 Apps (Enterprise, x64 and x86)
Microsoft 365 for macOS
Microsoft Office 2019, Office 2021 LTSC, and Office 2024 LTSC (Windows and macOS)
Microsoft Word 2016 (x64 and x86)

Discovery Timeline

2026-09-08 - CVE-2026-69719 published to the National Vulnerability Database (NVD)
2026-09-08 - Last updated in NVD database

Technical Details for CVE-2026-69719

Vulnerability Analysis

The vulnerability is a buffer over-read in the Word document parsing logic. When Word processes a malformed record, the parser reads past the end of an allocated buffer. The out-of-bounds bytes are then incorporated into internal structures that the attacker can indirectly observe. This exposes fragments of adjacent heap memory that may include text from other open documents, decrypted content, or authentication material cached in the process.

The issue impacts confidentiality only. Integrity and availability are not affected, and the vulnerability does not grant code execution. The current EPSS probability sits near the lower end of exploited vulnerabilities, and no public proof-of-concept or in-the-wild activity has been reported at time of writing.

Root Cause

The defect is classified under CWE-126: Buffer Over-read. The parser fails to validate that a length or offset field embedded in the document stays within the bounds of the containing buffer. A crafted structure with an inflated size field causes the read loop to continue past the buffer terminator into unrelated memory.

Attack Vector

The attack is network-delivered but requires user interaction. An attacker distributes a weaponized .docx, .doc, .rtf, or related Word-supported file through phishing, a shared drive, or a compromised website. When the target opens the file, Word processes the malformed record and leaks memory. The leaked data may be exfiltrated through embedded objects, remote template references, or subsequent user actions.

No verified exploit code is publicly available. See the Microsoft Security Update Guide for vendor-supplied technical details.

Detection Methods for CVE-2026-69719

Indicators of Compromise

Inbound email attachments or download activity delivering Word documents from unverified external senders or newly registered domains.
Word processes (winword.exe) issuing outbound network requests to previously unseen hosts shortly after a document is opened.
Documents containing malformed OOXML parts, oversized length fields, or embedded remote template references.
Unexpected child processes or memory-dump-style artifacts spawned from a Word session.

Detection Strategies

Inspect Office telemetry for documents that trigger parser exceptions or protected-view escapes on affected Word builds.
Correlate document-open events with outbound HTTP or SMB connections initiated by winword.exe.
Apply YARA rules targeting anomalous record sizes and malformed structures in Word file formats.
Hunt for phishing campaigns delivering Word attachments to high-value mailboxes using content-based email filters.

Monitoring Recommendations

Ingest Microsoft 365 audit logs, endpoint process telemetry, and email gateway logs into a central analytics platform for correlation.
Track Office version and patch state across managed endpoints to identify unpatched hosts opening external documents.
Alert on user-reported phishing containing Word attachments and preserve the samples for parser analysis.

How to Mitigate CVE-2026-69719

Immediate Actions Required

Apply the Microsoft security update referenced in the Microsoft Security Update Guide to all affected Office installations.
Prioritize patching endpoints that routinely process external documents, including executive assistants, finance, HR, and legal users.
Verify the patched build number after deployment using File > Account > About Word or centralized configuration management.

Patch Information

Microsoft has published fixes for Microsoft 365 Apps, Microsoft 365 for macOS, Office 2019, Office 2021 LTSC, Office 2024 LTSC, and Word 2016. Consult the vendor advisory for build numbers per channel and platform. Managed devices should receive the update through Microsoft Update, Click-to-Run, or Intune update rings.

Workarounds

Enforce Protected View for documents originating from the internet and email attachments through Group Policy.
Block or quarantine Word file types at the email gateway for untrusted external senders until patching is complete.
Disable automatic download of remote content and linked images in Word to reduce exfiltration channels for leaked memory.
Restrict opening of legacy binary formats (.doc, .rtf) where business processes permit.

bash

# Enforce Protected View via Group Policy registry keys (per-user)
reg add "HKCU\Software\Microsoft\Office\16.0\Word\Security\ProtectedView" /v DisableInternetFilesInPV /t REG_DWORD /d 0 /f
reg add "HKCU\Software\Microsoft\Office\16.0\Word\Security\ProtectedView" /v DisableAttachmentsInPV  /t REG_DWORD /d 0 /f
reg add "HKCU\Software\Microsoft\Office\16.0\Word\Security\ProtectedView" /v DisableUnsafeLocationsInPV /t REG_DWORD /d 0 /f