CVE-2025-29979
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 · uneditedHeap-based buffer overflow 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 confidenceHeap-based buffer overflow vulnerability in Microsoft Office Excel that allows an unauthorized attacker to execute code locally. Exploitation requires the victim to open a specially crafted Excel file containing malformed data structures that trigger the overflow on the heap, potentially giving the attacker control over execution flow.
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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Identify installed Microsoft Excel versionOpen Excel, go to File > Account > About Excel, or run 'winword /?' from command prompt to check Office versionAffected if Version is 2016 or later (including Microsoft 365 Apps)
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Identify Microsoft Office versionOpen any Office app, go to File > Account > About [App], or check registry key HKLM\SOFTWARE\Microsoft\Office\ClickToRun\ConfigurationAffected if Office version is 2019, 2021, or 2024 (or Microsoft 365 Apps)
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Identify Microsoft Office Online Server version (if applicable)Check server version via Office Online Server administration or PowerShell: Get-ItemProperty HKLM:\SOFTWARE\Microsoft\Office\WebServer\15.0\SetupAffected if Office Online Server version is below 16.0.10417.20010
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Confirm Excel application is present and accessibleVerify excel.exe exists on the system at typical locations (C:\Program Files\Microsoft Office\root\Office## or C:\Program Files (x86)\Microsoft Office\root\Office##)Affected if Excel executable is present, indicating the software is installed and could be used to open a malicious file
Your environment is affected if Microsoft Excel or Office (2016, 2019, 2021, 2024, or Microsoft 365 Apps) is installed and a user could open Excel files, or if Office Online Server version is below 16.0.10417.20010.
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 · scoped16.0.10417.20010
Apply Microsoft security updates for Microsoft Office Excel immediately; instruct users to avoid opening Excel files from untrusted or unknown sources.
Apply Microsoft security update for CVE-2025-29979 (latest patched version via Windows Update or Microsoft Update Catalog)
- Enable automatic updates for Microsoft Office or Microsoft 365 to receive security updates automatically
- For standalone Office installations, apply the latest Microsoft security update for this vulnerability via Windows Update or the Microsoft Update Catalog
- Verify the update was installed successfully by checking installed updates in Windows Settings > Update & Security > Windows Update > View update history
- For organizations managing Office Online Server, upgrade to version 16.0.10417.20010 or later
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation2.0 h
- Implementation4.0 h
- Testing2.0 h
- Review / QA1.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2025-29979 — 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-2025-29979 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