n8n has a Webhook Node IP Whitelist Bypass via Partial String Matching

n8n is an open source workflow automation platform. From 1.36.0 to before 2.2.0, the Webhook node’s IP whitelist validation performed partial string matching instead of exact IP comparison. As a result, an incoming request could be accepted if the source IP address merely contained the configured whitelist entry as a substring. This issue affected instances where workflow editors relied on IP-based access controls to restrict webhook access. Both IPv4 and IPv6 addresses were impacted. An attacker with a non-whitelisted IP could bypass restrictions if their IP shared a partial prefix with a trusted address, undermining the intended security boundary. This vulnerability is fixed in 2.2.0.