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.