CVE-2026-86078: n8n: Prototype Pollution via Workflow Structure Summary Can Lead to Denial of Service
n8n is an open source workflow automation platform. Prior to 2.37.7 and 2.38.2, the Instance AI workflow summary used node names and connection keys from stored workflows as ordinary object keys. A workflow submitted through the REST API could contain proto or constructor, causing nested writes to reach Object.prototype in the main n8n process and disrupt later requests. The affected function is summarizeWorkflowStructure in packages/@n8n/instance-ai/src/tools/workflows/summarize-workflow.ts. This issue is fixed in versions 2.37.7 and 2.38.2.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
n8nto a version that resolves this vulnerability.Fixed in 2.37.7 - Upgrade
Upgrade
n8nto a version that resolves this vulnerability.Fixed in 2.38.2
Event History
Frequently Asked Questions
What access does an attacker need to trigger this issue?
An attacker needs the ability to submit a crafted workflow through the n8n REST API. The workflow must use special property names such as __proto__ or constructor in node names or connection keys.
What is the practical impact after exploitation?
Crafted workflow data can cause writes to Object.prototype in the main n8n process. This can disrupt subsequent requests and lead to denial of service.
Which versions contain the fix?
The issue is fixed in n8n versions 2.37.7 and 2.38.2. Versions prior to those releases are affected.