Summary A known vulnerability CVE-2026-33060 indicated tools including ckan_package_search and sparql_query that accept a base_url parameter had the risk of making HTTP requests to arbitrary endpoints without restriction. A fix was applied to filter out ip addresses. However, a method to bypass exists. Details CKAN MCP Server validates caller-supplied CKAN server URLs by inspecting only the parsed hostname string before issuing outbound HTTP requests. In "src/utils/http.ts", hostname aliases such as "ip6-localhost" are not equal to "localhost", are not dotted IPv4 literals, and are not bracketed IPv6 literals, so they pass the SSRF filter but can resolve to loopback when the server performs the request. A remote MCP caller that can invoke CKAN tools with a "server_url" can therefore make the server connect to local or private addresses and, for CKAN-shaped responses, receive response-derived data. Fix Replaced the single "hostname === 'localhost'" check with a blocked-hostname "Set" covering "ip6-localhost" and "ip6-loopback". Patched in commit "c761045a1b7c5f40d2626540dd2ef1d4feb91f8c". *** @aborruso/ckan-mcp-server thanks hibrian827 for responsibly disclosing this issue.