n8n Workflow API Prototype Pollution Privilege Bypass Vulnerability
n8n is an open source workflow automation platform. Prior to 1.123.61, 2.27.4, and, 2.28.1, an authenticated user with the default workflow:create permission could pollute Object.prototype through a crafted workflow saved, updated, or imported via the workflow API, allowing unauthenticated requests to be treated as a privileged user and exposing user and project listing endpoints. This issue is fixed in versions 1.123.61, 2.27.4, and 2.28.1.
Quick answer
n8n should be reviewed and updated if it matches the affected versions. The recommended fix is to apply the vendor-supported patched version or the mitigation steps below, then retest the public website with Fixnx.
Who is affected
Affected versions
- Before 1.123.61
- Before 2.27.4
- Before 2.28.1
Fixed versions
- 1.123.61
- 2.27.4
- 2.28.1
How to fix it
n8n is affected by a workflow API prototype pollution issue that can cause unauthenticated requests to be treated as privileged. Upgrade to 1.123.61, 2.27.4, 2.28.1, or a later fixed release for the branch in use. Because the impact can expose users and project listing endpoints, review workflow API activity and rotate secrets if unauthorized access is found.
- Inventory n8n versions and identify instances where users can create, update, or import workflows through the API.
- Upgrade affected deployments to 1.123.61, 2.27.4, 2.28.1, or a later fixed branch release.
- Restrict workflow:create, workflow import, and workflow update permissions to trusted users until patching is complete.
- Review workflow JSON, imported workflows, API requests, and audit logs for prototype pollution keys such as __proto__ or constructor.
- Check whether user, project, credential, or administrative endpoints were accessed unexpectedly.
- Rotate n8n API keys, credential store secrets, OAuth tokens, webhook secrets, and provider keys if privilege bypass is suspected.
- Redeploy from clean images and clear active sessions after applying the update.
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Verify the fix
- Confirm every n8n instance runs a fixed version for CVE-2026-59206.
- Validate crafted workflow payloads cannot pollute Object.prototype or bypass authorization.
- Review n8n logs for unauthorized user or project enumeration during the vulnerable period.
- Run workflow import, update, and normal execution regression tests after remediation.
- Run a Fixnx scan and confirm no public n8n admin or API surface is exposed unexpectedly.
Related categories
Trusted references
FAQ
What is affected by CVE-2026-59206?
n8n versions listed as affected should be reviewed: Before 1.123.61, Before 2.27.4, Before 2.28.1.
What should I fix first?
Start with internet-facing sites, admin panels, login flows, plugins, themes, modules, packages, and systems that process user-controlled input or sensitive data.
How do I confirm the fix worked?
Apply the patched version or mitigation, clear caches where relevant, retest the affected workflow, and run a new Fixnx scan to verify public website exposure signals.
Why can this risk appear in multiple categories?
A vulnerability can belong to more than one platform or ecosystem. Fixnx keeps one canonical risk page while also listing it in every relevant category.