CVE-2025-30383
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 confidenceType confusion vulnerability in Microsoft Office Excel allows an attacker to execute arbitrary code locally by opening a specially crafted Excel file that mishandles object types in memory.
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= 2016= 2019= 2021= 2024< 16.0.10417.20010CVSS 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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Check installed Excel versionOpen Excel, go to File > Account > About Excel (or File > Account > About in newer versions). Record the version number shown (e.g., 16.0.xxxxx.xxxxx).Affected if The version falls outside the following safe versions: Excel 2016 (16.0.xxxx), Office 2019, Office 2021, Office 2024, or Microsoft 365 Apps with versions that have not been patched after the CVE release date.
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Verify Excel 2016 versionIf using Excel 2016, run: winword.exe /? (or check installed programs in Control Panel). Confirm the version is 16.0.xxxx or later without corresponding security patch.Affected if Excel 2016 is installed without the May 2025 or later Office security update.
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Verify Office 2019/2021/2024 versionCheck Office version via File > Account > About Excel or via PowerShell: Get-ItemProperty 'HKLM:\SOFTWARE\Microsoft\Office\ClickToRun\Configuration' -ErrorAction SilentlyContinue | Select-Object VersionToReportAffected if Office 2019, 2021, or 2024 is installed without the May 2025 security update applied.
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Verify Microsoft 365 Apps versionOpen Excel > File > Account > About Excel. Check if Updates is enabled and Office is receiving automatic updates. Run: winword.exe /? to see full version string.Affected if Microsoft 365 Apps is installed and has not received the May 2025 Office security patch.
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Check Office Online Server version (if applicable)If using Office Online Server, run: Get-OfficeOnlineServerVersion or check the installed version in Programs and Features. Compare to 16.0.10417.20010.Affected if Office Online Server version is lower than 16.0.10417.20010.
Your environment is affected if any installed Excel version (2016, 2019, 2021, 2024, Microsoft 365, or Office Online Server) is missing the May 2025 security update for CVE-2025-30383.
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 data16.0.10417.20010
Apply Microsoft security updates for Office Excel immediately; avoid opening Excel files from untrusted sources.
- Consultation1.0 h
- Implementation1.0 h
- Testing1.0 h
- Review / QA1.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,200.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2025-30383 — 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-2025-30383 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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- 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