Summary
@aborruso/ckan-mcp-server: SSRF via base_url allows access to internal networks (Potential fix bypass of CVE-2026-33060)
Full technical description
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.
Impact
Untrusted input controls the target URL of a server-initiated request, which may reach internal services not otherwise accessible from outside. Typical impact: access to internal metadata services, internal APIs, or cloud credentials.
CVE-2026-53509 has a CVSS score of 5.7 (Medium). The vector is network-reachable, low privileges required, and user interaction required. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (0.4.106); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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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.
Frequently Asked Questions
- What is CVE-2026-53509? CVE-2026-53509 is a medium-severity server-side request forgery (SSRF) vulnerability in @aborruso/ckan-mcp-server (npm), affecting versions < 0.4.106. It is fixed in 0.4.106. Untrusted input controls the target URL of a server-initiated request, which may reach internal services not otherwise accessible from outside.
- How severe is CVE-2026-53509? CVE-2026-53509 has a CVSS score of 5.7 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which versions of @aborruso/ckan-mcp-server are affected by CVE-2026-53509? @aborruso/ckan-mcp-server (npm) versions < 0.4.106 is affected.
- Is there a fix for CVE-2026-53509? Yes. CVE-2026-53509 is fixed in 0.4.106. Upgrade to this version or later.
- Is CVE-2026-53509 exploitable, and should I be worried? Whether CVE-2026-53509 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2026-53509 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2026-53509? Upgrade
@aborruso/ckan-mcp-serverto 0.4.106 or later.