CVE-2026-55054
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 · uneditedOut-of-bounds read in Microsoft Office Excel allows an unauthorized attacker to disclose information over a network.
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 confidenceAn out-of-bounds read vulnerability exists in Microsoft Office Excel that allows an unauthorized attacker to read memory contents beyond allocated buffers. This information disclosure flaw is exploitable over a network and could enable attackers to obtain sensitive data from the application's memory space.
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< 16.111.26071215all versions< 16.111.26071215all versions< 16.0.10417.20175< 16.111.26071215CVSS 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
- Network
- Complexity
- Low
- Privileges
- None
- User interaction
- Required
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- None
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
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, or run 'winword --version' or check Programs and Features for Microsoft ExcelAffected if Excel is not installed, the system is not affected by this specific Excel vulnerability
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Determine the installed Office/Excel versionOpen Excel > File > Account > About Excel to see the version number, or open Word > File > Account > About Word and check for Office versionAffected if Version displays as 16.xxxx.xxxx - note this for the next comparison step
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Check if version is before the fixed releaseCompare your version number to the fixed build 16.111.26071215 (for Office 365, 2021, 2024) or 16.0.10417.20175 (for Office Online Server)Affected if If version is lower than 16.111.26071215 for Office 365/2021/2024, or lower than 16.0.10417.20175 for Office Online Server, the installation is vulnerable
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Check for Microsoft 365 Apps versionsOpen any Office app > File > Account > About [App] - for Microsoft 365 Apps, all versions are listed as affectedAffected if If using Microsoft 365 Apps subscription without the latest updates, the version is affected
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Verify recent security updates are appliedOpen Excel > File > Account > Update Options > Check for Updates, or check Windows Update history for recent Office security updatesAffected if If updates are not current or automatic updates are disabled, the vulnerability may still be present
A user is affected if they have Microsoft Excel installed with a version lower than 16.111.26071215 (Office 365/2021/2024) or 16.0.10417.20175 (Office Online Server), or are on Microsoft 365 Apps without latest patches.
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 · scoped16.0.10417.2017516.111.26071215
Apply Microsoft security updates for Office Excel as they become available through the regular patch management process. Verify that automatic updates are enabled or manually download patches from Microsoft's official channels.
Office 2021/2024/365: version 16.111.26071215 (May 2026 Patch Tuesday); Office Online Server: version 16.0.10417.20175
- Open any Office application (such as Excel)
- Go to File > Account
- Click on Update Options > Update Now
- Alternatively, check for updates via Windows Update: Settings > Update & Security > Windows Update > Check for updates
- Ensure the update version reaches 16.111.26071215 or higher for Office 2021/2024/365, or 16.0.10417.20175 or higher for Office Online Server
- Restart Office applications after the update completes
- Verify the installed version by going to File > Account > About Excel
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation2.0 h
- Implementation3.0 h
- Testing2.0 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 $2,272.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-55054 — 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-2026-55054 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