The ckan-mcp-server tool used for querying CKAN open data portals had an SSRF vulnerability (CVE-2026-61612) in versions prior to 0.4.108. The SSRF guard function validateServerUrl, introduced for earlier CVEs, only validated the hostname string without performing DNS resolution. This allowed attacker-controlled server_url parameters whose hostnames resolved to internal IP addresses, including loopback and cloud metadata IP 169.254.169.254, to bypass the guard and cause the server to issue unauthorized requests to internal services. This vulnerability is a third bypass of the same guard and extends the impact beyond previous CVEs by reaching the cloud metadata service. The vulnerability has a CVSS 3.1 base score of 5.7 (medium severity), with network attack vector, low attack complexity, requiring low privileges and user interaction, and resulting in high confidentiality impact but no integrity or availability impact. The issue is fixed in version 0.4.108 with an updated SSRF guard implementation.

Successful exploitation allows an attacker with low privileges and requiring user interaction to cause the ckan-mcp-server to send requests to internal network addresses, including loopback and cloud metadata service endpoints. This can lead to unauthorized disclosure of sensitive internal information (high confidentiality impact). There is no impact on integrity or availability. The vulnerability could be used to access sensitive metadata or internal services not normally accessible externally.

Version 0.4.108 of ckan-mcp-server contains an updated fix that properly addresses the SSRF vulnerability by improving the validateServerUrl guard to correctly handle DNS resolution and block internal addresses. Users should upgrade to version 0.4.108 or later to remediate this issue. No additional mitigation is required if the fixed version is deployed.