CVE-2026-50678
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 disclose information 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 confidenceA heap-based buffer overflow vulnerability exists in Microsoft Office Excel that allows an unauthorized local attacker to disclose sensitive information. The flaw stems from improper memory handling when Excel processes certain data structures, enabling the attacker to read heap memory contents beyond allocated buffers.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
CVSS 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
- Low
- Integrity
- Low
- Availability
- High
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:L/I:L/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 Excel and go to File > Account > About Excel to view the version, or check the Windows Registry at HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Office\ClickToRun\Configuration for the installationAffected if Excel is not present on the system - the vulnerability only applies if Excel is installed
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Identify the installed Excel versionIn Excel, click File > Account > About Excel and note the full version number displayed (for example, 16.0.XXXXX.XXXX for Office 2016 or newer, or 14.0/15.0 for older versions)Affected if Cannot determine version - vulnerability status cannot be assessed
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Compare version against CVE-2026-50678 fixed releasesCheck Microsoft Security Response Center or the relevant KB article for CVE-2026-50678 to find the patched version number, then compare your installed version against itAffected if Installed version is older than the patched version Microsoft released for this CVE
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Confirm the vulnerable file processing feature is accessibleExcel processes spreadsheet files (.xlsx, .xls, .xlsm) through the vulnerable code path - verify Excel can open and parse these filesAffected if Excel installation exists but cannot process spreadsheet files (unlikely scenario)
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Check for recent Office security updatesOpen Windows Settings > Update & Security > Windows Update > View update history, or go to Control Panel > Programs > Programs and Features > Installed Updates, and look for recent Microsoft Office security patchesAffected if No security updates for Office have been installed since the CVE-2026-50678 patch release date
The environment is affected if Microsoft Excel is installed with a version lower than the patched version Microsoft released for CVE-2026-50678.
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 the latest Microsoft Office security updates and patches. Verify that Microsoft Defender or equivalent endpoint protection has updated detection definitions for Office-related exploits.
- 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-2026-50678 — 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-2026-50678 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