CVE-2026-21523
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 · uneditedTime-of-check time-of-use (toctou) race condition in GitHub Copilot and Visual Studio allows an authorized attacker to execute code over a network.
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 time-of-check time-of-use (TOCTOU) race condition vulnerability in GitHub Copilot and Visual Studio allows an authorized attacker to execute arbitrary code over a network by exploiting a window between security checks and code execution.
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 data< 1.109.2CVSS 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
- Low
- User interaction
- Required
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:L/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 Visual Studio Code installationCheck if VS Code is installed by running 'code --version' in command prompt or PowerShell, or look for Visual Studio Code in the Start menu or Program FilesAffected if Visual Studio Code is installed on the system
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Identify installed VS Code versionRun 'code --version' or 'code -v' in terminal to retrieve the exact version number. Alternatively, open VS Code and go to Help > About to view the versionAffected if The version returned is below 1.109.2 (e.g., 1.109.1, 1.108.x, or earlier)
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Check for GitHub Copilot extensionOpen VS Code Extensions view (Ctrl+Shift+X) and search for 'GitHub Copilot' in the installed extensions list, or run 'code --list-extensions' in terminalAffected if GitHub Copilot extension is installed and enabled in Visual Studio Code
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Verify network-accessible code execution pathsReview VS Code settings (File > Preferences > Settings) for remote development extensions (Remote-SSH, Containers, WSL) or examine if the workspace is connected to a network share or remote repositoryAffected if Remote development features or network-accessible workspaces are enabled and the VS Code version is below 1.109.2
A system is affected if Visual Studio Code version is below 1.109.2 and has GitHub Copilot or remote development extensions enabled with network-accessible execution paths.
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 · scoped1.109.2
Apply vendor patches when available; restrict network access to minimize exposure until patches are deployed.
Visual Studio Code 1.109.2 or later
- Open Visual Studio Code
- Go to the 'Help' menu and select 'Check for Updates' (or press Ctrl+Shift+P and run 'Check for Updates')
- Allow Visual Studio Code to download and install the available update
- Restart Visual Studio Code after the update completes
- Verify the installed version is 1.109.2 or later by going to Help > About
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation4.0 h
- Implementation2.0 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 $4,928.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-21523 — 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-2026-21523 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