CVE-2026-44818
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 · uneditedConcurrent execution using shared resource with improper synchronization ('race condition') 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 confidenceA race condition vulnerability exists in Microsoft Office Excel where concurrent execution leads to improper synchronization of shared resources. This allows an unauthorized attacker to execute code locally with the privileges of the current user. The vulnerability stems from the application failing to properly serialize access to critical sections during concurrent operations.
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 versionsall versionsCVSS 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
- High
- Privileges
- None
- User interaction
- Required
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:L/AC:H/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.
-
Verify Microsoft Excel is installedOpen Windows Settings > Apps > Apps & features, or run 'Get-ItemProperty HKLM:\Software\Microsoft\Windows\CurrentVersion\Uninstall\* | Select-Object DisplayName, DisplayVersion | Where-Object {$_.DisplayName -like "*Excel*"}' in PowerShell to list installed Excel components.Affected if Microsoft Excel is present on the system
-
Confirm Office/Excel version falls within affected rangeOpen Excel, go to File > Account > About Excel, or run 'winword.exe /?' or 'excel.exe /?' from Command Prompt to display version information.Affected if Version is 2016 or later, or the product is Microsoft 365 Apps, Office 2019, Office 2021, Office 2024, or Office Online Server
-
Check for concurrent workbook sharing featureReview Excel settings: File > Options > Trust Center > Trust Center Settings > Privacy Options. Look for settings related to shared workbooks, collaboration, or concurrent file access.Affected if Workbook sharing or concurrent editing features are enabled and being used
-
Inspect recent Excel process behaviorUse Windows Task Manager or Process Explorer to observe Excel.exe activity. Look for unusual child processes or thread activity during file operations.Affected if Excel exhibits unexpected process behavior or spawns suspicious child processes when opening files
If Excel 2016 or later (including Microsoft 365, Office 2019/2021/2024, or Office Online Server) is installed, the system is potentially affected by this race condition vulnerability.
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 Microsoft security patches for Excel when available. Until then, enforce least privilege principles, restrict Excel execution to sandboxed environments where feasible, and monitor for suspicious process behavior indicative of race condition exploitation.
- Consultation4.0 h
- Implementation8.0 h
- Testing6.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $5,600.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-44818 — 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-2026-44818 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
Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.
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