n8n EUVD-2026-63259

Exploitation requires three concurrent conditions: first, the target n8n instance must use the MongoDB integration node in a workflow with Find, Delete, or Aggregate operations; second, the workflow must accept externally-controlled data - such as webhook payloads, HTTP parameters, or form submissions - and route that data into the MongoDB node's Query parameter without sanitization or strict type enforcement; third, the MongoDB database must be reachable from the n8n server. The CVSS 4.0 AT:P metric explicitly encodes these deployment-specific preconditions. Limiting factors include: workflows that use only static or developer-hardcoded queries are not exploitable regardless of version; n8n instances with no externally-facing workflow triggers are not directly exploitable from the internet; and MongoDB accounts provisioned with read-only permissions would prevent injection via Delete operations, though collection-wide reads via Find would still be reachable. The CVSS 4.0 PR:N metric confirms no attacker authentication is required against n8n itself, but the workflow trigger mechanism (e.g., webhook authentication headers) may impose additional access controls in specific deployments.

The CVSS 4.0 vector (AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:H/SA:H) rates the subsequent-system (MongoDB database) impact as High across all three pillars, while the vulnerable system (n8n itself) shows no direct impact - correctly reflecting that n8n is the injection point but MongoDB bears the operational consequences. The AT:P (Attack Requirements: Present) metric is the critical moderating factor: exploitation requires a workflow specifically configured to accept external input and route it unsanitized into a MongoDB node query, meaning not all n8n deployments are equally exposed. No EPSS data was provided in the input, which limits probabilistic risk quantification. The absence of a CISA KEV entry and no confirmed public exploit code reduce immediacy, but the High subsequent-system impact across integrity and availability - including the potential for full-collection deletion - means the practical blast radius for affected workflows is severe. The PR:N metric confirms that no attacker authentication is required against n8n itself, though the workflow trigger mechanism may impose its own access controls depending on deployment.

An attacker identifies an n8n instance with a publicly accessible webhook-triggered workflow that performs a MongoDB Find operation using a customer-supplied identifier (e.g., a product ID or user lookup). By sending a crafted webhook payload where the query field contains {"$ne": null} instead of a legitimate value, the attacker transforms the intended single-record lookup into a full-collection scan, retrieving all documents. If the workflow uses a Delete operation, the same operator injection triggers mass deletion of the entire collection without any authentication against n8n itself.