The @aborruso/ckan-mcp-server tool, used for querying CKAN open data portals, had a known SSRF vulnerability (CVE-2026-33060) where the base_url parameter could be used to make HTTP requests to arbitrary endpoints. A fix was applied to filter IP addresses, but prior to version 0.4.106, the hostname validation only checked for 'localhost' explicitly. Hostname aliases such as 'ip6-localhost' were not blocked and resolved to loopback addresses, allowing SSRF bypass. This flaw lets remote callers invoke CKAN tools with a server_url parameter that causes the server to connect to internal or private addresses and retrieve data from CKAN-shaped responses. Version 0.4.106 addressed this by replacing the single hostname check with a blocked-hostname set including 'ip6-localhost' and 'ip6-loopback'.

An attacker with the ability to invoke CKAN tools remotely can exploit this SSRF vulnerability to make the server perform HTTP requests to internal or private network addresses. This can lead to unauthorized access to internal services or sensitive data exposed by CKAN-shaped responses. The vulnerability has a CVSS score of 5.7 (medium severity) indicating a moderate impact primarily on confidentiality. There is no indication of integrity or availability impact. No known exploits in the wild have been reported.

A patch is available in version 0.4.106 that fixes the SSRF bypass by expanding the blocked hostname checks to include aliases such as 'ip6-localhost' and 'ip6-loopback'. Users should upgrade to version 0.4.106 or later to remediate this vulnerability. Until patched, users should avoid accepting untrusted input for the base_url or server_url parameters that control outbound HTTP requests.