Node.js permission model bypass via unchecked Unix Domain Socket connections (UDS)

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

not scored

EPSS

• CVE-2026-21636: 0.87% estimated exploitation activity in the next 30 days; percentile 58.85 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

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.

Published by the source

12 Jan 2026, 00:00 UTC

Last modified by the source

12 Jan 2026, 00:00 UTC

Source last checked

26 Oct 2026, 16:40 UTC

1. Revision 2 · published · 26 Oct 2026

   Published from vendor_advisory record nodejs-security-wg:core:162

2. Revision 1 · created · 26 Oct 2026

   Created from vendor_advisory record nodejs-security-wg:core:162

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# Patch Next advisory brief: CVE-2026-21636

Advisory: Node.js permission model bypass via unchecked Unix Domain Socket connections (UDS)
IDs: CVE-2026-21636
Record: https://patchnext.com/advisories/cve-2026-21636 (revision 2, source checked 26 Oct 2026, 16:40 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Unrated
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: node 25.3.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- runtime node: affected >= 25.0.0, < 25.3.0; fixed in 25.3.0

## Suggested inspection (read-only)
- runtime node: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on node.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://nodejs.org/dist/index.json (The nodejs.org release index dates the first patched release for CVE-2026-21636 to 2026-01-12.)
- Verified: https://raw.githubusercontent.com/nodejs/security-wg/main/vuln/core/162.json (Node.js security working group core entry 162 lists CVE-2026-21636 affecting node >=25.0.0 <25.3.0)

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