CVE-2026-55137
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.
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 confidenceHeap-based buffer overflow in Microsoft Office Excel that can be exploited by a local attacker opening a specially crafted malicious Excel file, potentially allowing arbitrary code execution with the user's privileges.
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 versions< 16.0.10417.20175CVSS 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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Confirm Microsoft Excel is installedOpen Excel, go to File > Account > About Excel, or run 'winword --version' or check Programs and Features for Microsoft ExcelAffected if Excel is not installed, the system is not vulnerable to this Excel-specific flaw
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Identify installed Excel versionIn Excel: File > Account > About Excel shows version and build number. Via command line: open cmd, run 'reg query "HKLM\SOFTWARE\Microsoft\Office\ClickToRun\Configuration" /v VersionToReport' or check Program Files for Excel.exe and right-click > Properties > Details for version infoAffected if Version matches an affected release: Excel 2016/2019/2021/2024, Microsoft 365 Apps, Office 365, or Office Online Server versions prior to 16.0.10417.20175 (for OOS)
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Check Office Click-to-Run version if applicableRun 'oscdimg.exe' or check HKLM\SOFTWARE\Microsoft\Office\ClickToRun\Configuration registry key for 'VersionToReport'Affected if Running Microsoft 365 or Office 2016+ via Click-to-Run and version is older than current patch level
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Determine if user opens untrusted Excel filesReview user behavior or endpoint monitoring for Excel process (EXCEL.EXE) opening files from untrusted or email attachments sources. Check email gateway or endpoint protection logs for recent Excel attachmentsAffected if Users routinely open Excel attachments from untrusted sources without prior validation
System is affected if Microsoft Excel is installed with a version that falls within the affected ranges (Excel 2016 through 2024, Microsoft 365 Apps, Office 365, or Office Online Server versions before 16.0.10417.20175) and users can open potentially malicious Excel files.
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 data16.0.10417.20175
Apply Microsoft security updates for Office Excel when available; implement file filtering/monitoring for untrusted Excel attachments; restrict user privileges to limit impact of successful exploitation.
- Consultation2.0 h
- Implementation4.0 h
- Testing3.0 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 $2,800.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-55137 — 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-2026-55137 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