# 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.

- **Severity:** Medium 5.7 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:N/A:N`)
- **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:** Yes
- **Published:** 21 Aug 2026
- **Updated:** 21 Aug 2026
- **Also known as:** GHSA-g84h-j7jj-x32p

## 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 (Server-Side Request Forgery)

## Which versions are affected by CVE-2026-53509?

2 open source packages ship an affected version, including @aborruso/ckan-mcp-server.


| Package | Ecosystem | 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.

## Is CVE-2026-53509 being exploited?

There is no known exploitation of CVE-2026-53509 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-53509 and fix it if it is affected.

What it is: 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.
Exploitation: There is no known exploitation of CVE-2026-53509 in the wild and no public exploit code.

Affected packages and fixed versions:
- @aborruso/ckan-mcp-server (npm): affected all versions; fixed in 0.4.106
- @aborruso/ckan-mcp-server (npm): affected all versions; fixed in 0.4.106

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-53509/ (Markdown: https://insights.sbomify.com/CVE-2026-53509/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-53509
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-53509
- OSV: https://osv.dev/vulnerability/CVE-2026-53509

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-53509/
Summaries are generated and may contain mistakes; the official description above is the record.