CVE-2026-110842

n8n before 2.41.4 and 2.42.x before 2.42.1 contains a prototype pollution vulnerability in the MCP workflow-validation tool, whose interpreter evaluates caller-supplied code in the main process, reads inherited properties, and permits assignment onto shared prototypes. An authenticated member holding only a workflow:read grant can replace a built-in method with one returning a truthy value so server-side permission checks accept unheld scopes, enabling takeover of owner accounts not protected by MFA.

• https://github.com/n8n-io/n8n/security/advisories/GHSA-5jr4-xmvf-frmj
• https://www.vulncheck.com/advisories/n8n-before-2.41.4-and-2.42.1-prototype-pollution-via-mcp-workflow-validation-interpreter