Novu provides an API for sending notifications through multiple channels. Prior to 3.17.0, validateUrlSsrf in libs/application-generic/src/utils/ssrf-url-validation.ts uses the isPrivateIp deny-list without covering the RFC6598 100.64.0.0/10 shared address space or its IPv4-mapped IPv6 forms. The workflow HTTP request step and webhook filter condition can therefore send server-side requests when a configured literal address or resolved hostname falls in that range. In Alibaba Cloud, 100.100.100.200 may expose instance metadata, while self-hosted and multi-tenant deployments may expose provider-internal services, private infrastructure, service meshes, or VPN resources reachable through CGNAT addressing. This issue is fixed in version 3.17.0.