CVE-2026-55134
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedStack-based buffer overflow in Microsoft Office Word allows an unauthorized attacker to execute code locally.
In the news
Third-party coverage- Microsoft July 2026 Patch Tuesday fixes massive 570 flaws, 3 zero-days
- Microsoft CVE Summary - Bleeping Computer
Surfaced from public web coverage — external links open in a new tab.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · moderate confidenceStack-based buffer overflow vulnerability in Microsoft Office Word enables local attackers to execute arbitrary code by overflowing a stack-allocated buffer. The CVSS 7.8 indicates high severity with low attack complexity and no privileges required for exploitation.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE dataall versionsall versionsall versionsall versionsall versions< 16.0.19725.20434= 2016= 2019= 2016CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Local
- Complexity
- Low
- Privileges
- None
- User interaction
- Required
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Verify Microsoft Word installationOpen Control Panel > Programs and Features, or run 'Get-ItemProperty HKLM:\Software\Microsoft\Windows\CurrentVersion\Uninstall\* | Select-Object DisplayName, DisplayVersion' in PowerShell to list installed Microsoft Office/Word applicationsAffected if Microsoft Word is listed as installed with any version matching the affected product ranges (Office 2016, 2019, 2021, 2024, Microsoft 365 Apps, or Microsoft 365)
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Check installed Office/Word version numberOpen Word, go to File > Account > About Word, or run 'winword.exe /?' from Command Prompt to display version informationAffected if The displayed version matches Microsoft Word 2016 specifically, or falls within Office 2019/2021/2024/Microsoft 365 versions listed as affected
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Confirm Microsoft 365 Apps or Office 365 installationOpen any Microsoft 365 app, go to File > Account, or check via 'Get-ItemProperty HKLM:\SOFTWARE\Microsoft\Office\ClickToRun\Configuration' in PowerShellAffected if Microsoft 365 Apps or Microsoft 365 subscription products are installed (listed as all versions affected)
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Check SharePoint Server version if applicableOpen SharePoint Central Administration > System Settings > Manage servers in this farm, or run 'Get-SPFarm | Select-Object BuildVersion' in SharePoint Management ShellAffected if SharePoint Server 2016 or 2019 is installed, or version is earlier than 16.0.19725.20434
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Identify Word component in Office installationCheck for WINWORD.EXE presence in typical Office installation paths (C:\Program Files\Microsoft Office\root\Office## or C:\Program Files (x86)\Microsoft Office\Office##), or query registry HKLM:\SOFTWARE\Microsoft\Windows\CurrentVersion\App Paths\WINWORD.EXEAffected if WINWORD.EXE executable exists on the system, confirming Word is installed
Your environment is affected if Microsoft Word (any version for Microsoft 365/Office 2019-2024, or version 2016 specifically) or vulnerable SharePoint Server versions are installed on your system.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
dbcve · scoped16.0.19725.20434
Apply Microsoft security updates for Office Word as they become available. Until a patch is released, restrict opening untrusted Word documents and monitor for suspicious Word processes.
Apply Microsoft security updates via Windows Update/Microsoft Update; for SharePoint Server, upgrade to version 16.0.19725.20434 or later
- Check Windows Update or Microsoft Update for the latest Microsoft Office security patches
- If automatic updates are enabled, ensure they are applied automatically
- For SharePoint Server, update to version 16.0.19725.20434 or later
- After patching, verify the update was successfully applied via Office app version information
- Restart affected systems if required by the update
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation3.0 h
- Implementation4.0 h
- Testing3.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,408.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-55134 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-55134 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.
- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
- No weaponised exploit code, or anything meant to cause harm
- No spam, self-promotion, credentials, or personal data