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Node.jsApplication

CVE-2026-21636

CRITICAL · 10.0 CVSS v3.1 Published 2026-01-20
Fix available
A fix is available. Upgrade to 25.3.0 or later.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click

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 · unedited
A flaw in Node.js's permission model allows Unix Domain Socket (UDS) connections to bypass network restrictions when `--permission` is enabled. Even without `--allow-net`, attacker-controlled inputs (such as URLs or socketPath options) can connect to arbitrary local sockets via net, tls, or undici/fetch. This breaks the intended security boundary of the permission model and enables access to privileged local services, potentially leading to privilege escalation, data exposure, or local code execution. * The issue affects users of the Node.js permission model on version v25. In the moment of this vulnerability, network permissions (`--allow-net`) are still in the experimental phase.

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 · high confidence

Node.js v25's experimental permission model (--permission) incorrectly treats Unix Domain Socket (UDS) connections as non-network, allowing them to bypass --allow-net restrictions. Attacker-controlled inputs like URLs or socketPath options in net, tls, or undici/fetch can connect to arbitrary local sockets, breaking the security boundary and enabling access to privileged local services.

MitigationAvoid using untrusted input with socketPath options; consider disabling the experimental permission model until the patch is available; implement additional input validation for socket paths.

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
Node.jsApplication
Affected:>= 25.0.0, < 25.3.0

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
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Changed
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/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 checks

Work through these to decide whether this CVE applies to you.

  1. Check Node.js version
    Run 'node --version' to determine the installed Node.js version
    Affected if Version is >= 25.0.0 and < 25.3.0
  2. Verify permission model is enabled
    Check if Node.js is launched with --experimental-permission flag or if process.permission is defined in the application
    Affected if The experimental permission model is enabled (--experimental-permission flag present or process.permission exists)
  3. Confirm network restrictions are in place
    Check if Node.js is launched without --allow-net or with --allow-net set to false/limited values
    Affected if --allow-net is explicitly restricted or not granted in the permission configuration
  4. Identify applications using network APIs with user input
    Review code for usage of net.connect(), tls.connect(), undici.fetch(), or node:net/node:tls/node:fetch with socketPath or URL inputs that could be user-controlled
    Affected if The application passes user-supplied socketPath options or URLs to network APIs without sanitization

You are affected if running Node.js 25.0.0-25.2.x with the experimental permission model enabled and with network restrictions (--allow-net not granted), and your application uses network APIs with user-controlled socketPath or URL inputs that could reference Unix Domain Sockets.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

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 · scoped
Upgrade available Upgrade to 25.3.0 or later
Fixed in 25.3.0
Interim mitigation

Avoid using untrusted input with socketPath options; consider disabling the experimental permission model until the patch is available; implement additional input validation for socket paths.

Recommended fix High confidence

Node.js 25.3.0 or later

  1. Check current Node.js version by running: node --version
  2. If running a version >= 25.0.0 and < 25.3.0, plan for upgrade
  3. Upgrade to Node.js 25.3.0 or later using your preferred package manager (nvm, n, or official installers)
  4. Verify the new version: node --version
  5. Re-test your application with the --permission flag to confirm the security boundary is enforced correctly
Caveat Minor version upgrades within v25 typically have minimal breaking changes, but review the Node.js v25.3.0 release notes for any changes that may affect your application

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Node.js Scoped from the published advisory
  • Consultation8.0 h
  • Implementation16.0 h
  • Testing12.0 h
  • Review / QA8.0 h
44.0 hours of engineering $7,720
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-21636 in production — separate from our analysis above.

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What this is

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.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
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