CVE-2026-53509 @aborruso/ckan-mcp-server: SSRF via base_url allows access to internal networks (Potential fix bypass of CVE-2026-33060)
Attackers can bypass SSRF filters using hostname aliases to access internal networks and retrieve data from local services.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2026-53509?
CVE-2026-53509 is a medium-severity server-side request forgery vulnerability in ondata ckan-mcp-server, published on 21 Aug 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.
Official description
CKAN MCP Server is a tool for querying CKAN open data portals. 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 prior to version 0.4.106. 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. The updated fix in version 0.4.106 replaced the single `hostname === 'localhost'` check with a blocked-hostname `Set` covering `ip6-localhost` and `ip6-loopback`.
Weakness: CWE-918
Which versions are affected by CVE-2026-53509?
2 open source packages ship an affected version, including @aborruso/ckan-mcp-server.
| Package | Affected | Fixed in |
|---|---|---|
@aborruso/ckan-mcp-server npm | All versions | 0.4.106 |
@aborruso/ckan-mcp-server npm | All versions | 0.4.106 |
How do I fix CVE-2026-53509?
Upgrade @aborruso/ckan-mcp-server to 0.4.106 or later.
Upgrade, and send outbound requests through an allow-list that blocks internal addresses. More about Server-side request forgery.
Is CVE-2026-53509 being exploited?
There is no known exploitation of CVE-2026-53509 in the wild and no public exploit code.
Sources
Also known as GHSA-g84h-j7jj-x32p.