highCVE-2026-59206Jul 22, 2026

CVE-2026-59206: n8n Prototype Pollution via Workflow Credentials

Shubham Kandhare
Security Engagement Manager, SecureLayer7

Any authenticated n8n user can poison the shared JavaScript prototype through a crafted workflow, letting unauthenticated callers enumerate every account's email, role, and MFA status.

Packagen8n
Ecosystemnpm
Affected< 1.123.61
Fixed in1.123.61

The problem

n8n's workflow save, update, and import API endpoints accept credential objects that are merged into JavaScript objects without sanitising prototype-clobbering keys such as __proto__ or constructor.prototype.

Because Node.js runs all workflows in a single long-lived process, a successful pollution persists globally. Unauthenticated HTTP requests are then evaluated against the polluted prototype and can be treated as a privileged session, exposing the /users and /projects listing endpoints to anyone on the network.

The pollution can also crash parts of the instance until it is restarted.

The fix

Upgrade to n8n 1.123.61, 2.27.4, or 2.28.1. If you cannot upgrade immediately, restrict the workflow:create and workflow:update permissions to fully trusted users only and limit network access to the n8n instance. These workarounds reduce exposure but do not eliminate the risk.

Reported by Jubke.

References: [1][2][3][4][5]

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