The vulnerability enables injection of query operators into Elasticsearch and Google Cloud Firestore document queries built by the n8n workflow engine. By crafting an expression containing quote and brace characters, an attacker can close the intended field and add new query operators, turning a single‑document lookup into a full‑collection read. This results in unintended disclosure of potentially sensitive data stored in the n8n instance. The weakness is a query injection flaw (CWE‑943).

Versions of n8n prior to 2.35.4 and the 2.36.x series before 2.36.2 are affected. The issue is addressed in n8n 2.36.2 and later, and also in the 2.35.4 release. Organizations using older releases should identify and upgrade accordingly.

The CVSS score of 6.3 rates the vulnerability as medium severity. No EPSS score is published and the vulnerability is not listed in the CISA KEV catalog. The likely attack vector is remote exploitation of the n8n workflow definitions that accept user‑supplied expressions. If an attacker can influence those expressions—either through malicious workflow input or by modifying a workflow configuration—they can execute the injection and retrieve data beyond the intended scope. No privilege escalation is required beyond the normal permissions required to use the affected workflow nodes.