fkie_cve-2026-76894

CKAN MCP Server is a tool for querying CKAN open data portals. Prior to 0.4.112, the DataStore table UI in src/resources/datastore-table-ui.ts accepts window message events without validating event.origin and sends JSON-RPC messages through postMessage with a wildcard target origin. A frame that can reach the embedded document can inject fabricated fields or records, spoof pending ui/initialize responses, disrupt the MCP UI handshake, or receive outbound messages when the resource is embedded by an untrusted parent. Values are HTML escaped, so the demonstrated content injection is display spoofing rather than script execution, and exploitability depends on the host embedding model. This issue is fixed in version 0.4.112.

GHSA-vqff-r82h-9crc — ckan-mcp-server: DataStore Table UI resource does not validate postMessage origin (in) and posts to targetOrigin "*" (o…

Affected: npm: @aborruso/ckan-mcp-server

## Summary

The MCP Apps UI resource (an interactive DataStore table rendered in the host's webview/iframe) communicates with its parent via `postMessage`. Its inbound `message` listener performs no `event.origin` validation, and its outbound messages are sent with target origin `'*'`. Any window/frame able to reach the document can inject data into the table and interfere with the MCP UI handshake, and the UI's own JSON-RPC messages are broadcast without an origin restriction.

## Affected code

`src/resources/datastore-table-ui.ts` (inline HTML):

```js window.addEventListener('message', function (event) { var msg = event.data; // no check of event.origin if (!msg || typeof msg !== 'object') return; if (msg.id !== undefined && _pending[msg.id]) { ... resolve/reject pending MCP request ... } ... if (data && (data.fields || data.records)) initTable(data); // renders attacker-supplied data });

// outbound: window.parent.postMessage({ jsonrpc: '2.0', id: id, method: method, params: params || {} }, '*'); mcpNot: window.parent.postMessage({ jsonrpc:'2.0', method:method, params:params||{} }, '*'); ```

There is no allowlist of accepted origins for inbound messages and no fixed target origin for outbound messages.

## Impact

- **Content spoofing.** A frame that can `postMessage` to the UI can supply arbitrary `fields`/`records`, causing the table to render fabricated rows and links (e.g. a phishing `__link_url`) that appear to come from the que…

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fkie_cve-2026-76894

GHSA-vqff-r82h-9crc — ckan-mcp-server: DataStore Table UI resource does not validate postMessage origin (in) and posts to targetOrigin "*" (o…