CVE-2026-44817
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 · uneditedAccess of resource using incompatible type ('type confusion') in Microsoft Office Excel allows an unauthorized attacker to execute code locally.
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 confidenceThis is a type confusion vulnerability in Microsoft Office Excel where the software improperly handles resource access with incompatible types, allowing an unauthorized attacker to execute code locally on the affected system.
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 versions= 2016all versionsall versionsall versionsall versionsall versionsCVSS 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 Excel is installedOpen Windows Settings > Apps > Apps & features, or run 'Get-ItemProperty HKLM:\Software\Microsoft\Windows\CurrentVersion\App*Paths\EXCEL.EXE' in PowerShell to locate Excel.exeAffected if Excel is not found on the system, the user is not affected by this Excel vulnerability
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Determine installed Excel versionOpen Excel, go to File > Account > About Excel, or run 'winver' and check under Office programs, or use: Get-ItemProperty 'HKLM:\Software\Microsoft\Office\ClickToRun\Configuration' | Select-Object PlatformToVersionAffected if The installed version is Excel 2016 or later (2016, 2019, 2021, 2024) or any Microsoft 365/Office version, meaning it falls within the affected range
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Check if security updates have been appliedOpen Excel, go to File > Account > Update Options > Update Now, or check Windows Update history for recent Excel/Office security patchesAffected if No recent security updates for Excel have been installed, indicating the vulnerability may remain unpatched
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Confirm file opening behavior is enabledThe vulnerability triggers when opening a specially crafted Excel file; verify that Excel can open .xlsx/.xls/.xlsm files without restrictionsAffected if Users can open Excel files from any source, which is the standard behavior required for exploitation to occur
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Verify Excel executable file locationLocate EXCEL.EXE typically at C:\Program Files\Microsoft Office\root\Office## or C:\Program Files (x86)\Microsoft Office\root\Office## (where ## is version number)Affected if The Excel executable exists in standard Office installation paths, confirming the vulnerable software is present
If Excel is installed with version 2016 or later (including Microsoft 365, Office 2019/2021/2024) and recent security updates have not been applied, the environment is likely affected by this type confusion vulnerability.
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.
From vendor dataApply Microsoft security updates for Office Excel as they become available, and consider implementing application control policies to restrict Excel from opening untrusted files from unknown sources.
- Consultation4.0 h
- Implementation2.0 h
- Testing4.0 h
- Review / QA2.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-44817 — 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-2026-44817 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