CVE-2026-55948
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 · uneditedUse after free 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 confidenceThis is a use-after-free (UAF) vulnerability in Microsoft Office Excel where the application continues to use a memory pointer after it has been freed. An attacker can exploit this by crafting a malicious Excel file that triggers the UAF condition, allowing arbitrary code execution with the privileges of the current user.
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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Identify installed Excel versionOpen Excel, go to File > Account > About Excel. Alternatively, run PowerShell: Get-ItemProperty 'HKLM:\SOFTWARE\Microsoft\Office\ClickToRun\Configuration' | Select-Object PlatformVersion,VersionToReportAffected if Version is 2016 or later, or is part of Microsoft 365 Apps, Office 2019, 2021, or 2024 (all versions listed as affected)
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Check Office suite version via registryRun PowerShell: Get-ItemProperty 'HKLM:\SOFTWARE\Microsoft\Office\ClickToRun\Configuration' | Select-Object ProductReleaseIdsAffected if ProductReleaseIds contains any of the affected Office products (365, 2019, 2021, 2024)
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Verify Office Online Server version (if applicable)For Office Online Server, check version by running: Get-OfficeWebAppsServer | Select-Object VersionAffected if Version is earlier than 16.0.10417.20175 (the fixed version for Office Online Server)
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Confirm Excel is accessible to usersCheck if Excel.exe exists on endpoints: Get-ChildItem -Path 'C:\Program Files\Microsoft Office' -Recurse -Filter 'Excel.exe' -ErrorAction SilentlyContinue | Select-Object FullNameAffected if Excel is installed and accessible to users who can open files from external sources
You are affected if you have any version of Excel from 2016 onward, Microsoft 365 Apps, Office 2019/2021/2024, or Office Online Server versions prior to 16.0.10417.20175.
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 the official Microsoft security update for Excel when available. Until then, restrict opening Excel files from untrusted sources and ensure users run with least privilege. Consider enabling Office Protected View for potentially risky documents.
- Consultation6.0 h
- Implementation12.0 h
- Testing8.0 h
- Review / QA4.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $8,448.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-55948 — 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-2026-55948 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