CVE-2026-85170

n8n's Gmail (v1) and Brevo nodes pass message content to the mail composer without validating that it is a string (CWE-20), so non-string values are mishandled. An authenticated user who is able to run a workflow can supply an expression that resolves to an object with a 'path' or 'href' property, causing the composer to read a local file accessible to the n8n process or fetch an internal URL (SSRF) instead of sending the intended text. The attacker gains disclosure of sensitive local files (such as configuration or credentials readable by the n8n process) or access to internal network services, with the retrieved content attached to an outgoing email that provides an exfiltration channel. All n8n deployments on versions before 1.123.73, 2.35.4, or 2.36.2 that use the affected nodes are exposed, though exploitation requires valid credentials and workflow-run privileges, which limits remote attackers to multi-tenant or broadly shared instances. Exploitation has not been reported: EPSS is 0.2% (14th percentile), the issue is not in CISA KEV, and no public proof-of-concept is known.

What to do: Upgrade n8n to 1.123.73, 2.35.4, or 2.36.2 (matching your release branch) or later. Until then, restrict who can create and run workflows, and review workflows using the Gmail (v1) or Brevo nodes for expressions that can resolve to objects with 'path' or 'href' properties. Check n8n process logs and outbound/internal requests for signs of unexpected file reads or internal URL fetches.