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High

Out-of-bounds read RCE in Microsoft Office Word

IdentifiersCVE-2026-20944CWE-125· Out-of-bounds Read

CVE-2026-20944 is a Microsoft Office Word remote code execution vulnerability caused by an out-of-bounds read. The available source material identifies the flaw as affecting Microsoft Office Word and states that successful exploitation allows an unauthorized attacker to execute code locally. Multiple summaries further indicate the bug is triggered through a crafted malicious Word/Office document and that, in some deployment scenarios, the Outlook Preview Pane may be a viable attack vector, allowing exploitation without the user explicitly opening the document. The vulnerability is referenced by Microsoft in the MSRC Update Guide and is mapped to CWE-125.

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ANALYST BRIEF

Impact, mitigation & remediation

What it means. What to do now. Patch path, mitigations, and the assume-compromise checklist.

Impact

What an attacker gets, and what they’ve been doing with it.

Successful exploitation can result in arbitrary code execution in the context of the targeted user. Because the flaw is document-driven, it can be used for initial compromise via phishing or other malicious file delivery mechanisms. Where Preview Pane handling is applicable, the user-interaction barrier may be reduced, increasing the likelihood of compromise. The resulting access could enable installation of malware, data theft, persistence, and follow-on lateral movement depending on the privileges of the compromised user.

Mitigation

If you can’t patch tonight, do this now.

Until patches are fully deployed, reduce exposure to untrusted Word/Office documents delivered by email, web download, or shared storage; disable or restrict use of the Outlook Preview Pane where operationally feasible, since the content indicates it may be a valid attack vector; enforce Protected View and related Office hardening controls where available; and limit execution impact through least-privilege user accounts, application control, and email/content filtering for malicious attachments.

Remediation

Patch, then assume compromise.

Apply the Microsoft security updates for CVE-2026-20944 through the relevant Office servicing channel. The provided content indicates affected product lines include Microsoft 365 Apps for Enterprise and Microsoft Office LTSC for Mac 2021/2024, with fixes delivered via Click-to-Run or release-note-based updates depending on platform. Organizations should use the MSRC Update Guide entry for CVE-2026-20944 to identify the exact patched builds applicable to their Office/Word deployments and ensure all supported Word/Office installations are updated.
PUBLIC EXPLOITS

Exploits

No public exploits tracked yet. Mallory keeps watching.

VALID 0 / 0 TOTALView more in app

No public exploit code observed for this vulnerability.

EXPOSURE SURFACE

Affected products & vendors

Products and vendors Mallory has correlated with this vulnerability. Open in Mallory to drill down to specific CPE configurations and version ranges.

VendorProductType
Microsoft Corporation365 Appsapplication
Microsoft CorporationOffice Long Term Servicing Channelapplication
Microsoft CorporationOffice Macos 2021application
Microsoft CorporationOffice Macos 2024application

Vendor-confirmed product mapping. Mallory continuously reconciles this list against your asset inventory.

What this page doesn’t show

The version that knows your environment.

This page is what’s public. Mallory adds the parts that aren’t: which of your assets are affected, which adversaries are exploiting it right now, which detections to deploy, and what to do tonight.
Exposure mapping

Query your assets running an affected version, and investigate the blast radius.

Threat actor evidence

Every observed campaign linking this CVE to a named adversary.

Associated malware

Malware families riding this exploit, with evidence and IOCs.

Detection signatures

YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.

Vendor-by-vendor mapping

Cross-references every affected SKU, including bundled OEM variants.

Social activity3

Community discussion across Reddit, Mastodon, and other social sources.