CKAN MCP Server: DataStore Table UI resource does not validate postMessage origin (in) and posts to targetOrigin "*" (out)

CISA KEV is observed exploitation evidence. FIRST EPSS is a dated prediction of exploitation in the next 30 days. Missing scores are unknown. This collector requests predictions only for explicit CVE aliases in the public NuGet archive; Microsoft release views retain their existing prediction scope.

No collected risk observation for these identifiers. This does not establish absence of exploitation or a zero probability.

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.

Source published

3 Nov 2026 20:33:35 UTC

Source modified

3 Nov 2026 20:33:35 UTC

Observed here

3 Nov 2026 22:57:17 UTC

Source terms

CVE Program Terms of Use

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: cve-program · CVE Program Terms of Use. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS 3.1 · 3.1 CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:N/A:N

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.

Source published

Nov 3, 2026, 8:33:35 PM (timezone not stated)

Source modified

Nov 3, 2026, 8:33:35 PM (timezone not stated)

Observed here

7 Nov 2026 14:28:57 UTC

Source terms

ENISA EUVD · source terms and attribution apply

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: euvd · ENISA EUVD · source terms and attribution apply. Source text is retained; field grouping and change labels are provided by ChangeIntel.

EUVD CVSS 3.1 · 3.1 CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:N/A:N

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.

Source published

3 Nov 2026 21:17:43 UTC

Source modified

3 Nov 2026 21:17:43 UTC

Observed here

4 Nov 2026 20:55:56 UTC

Source terms

NIST NVD usage terms; underlying source attribution retained

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: nvd · NIST NVD usage terms; underlying source attribution retained. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS 3.1 · [email protected] · Secondary · 3.1 CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:N/A:N

## 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 queried portal. (Values are HTML-escaped, so this is display spoofing, not script injection — no XSS.) - **Handshake/UX interference.** Because inbound messages matching a pending `id` resolve/reject the UI's MCP requests, an attacker frame can spoof responses to the `ui/initialize` handshake or otherwise disrupt the panel. - **Outbound leakage.** Posting to `'*'` means the UI's JSON-RPC messages are delivered to whatever the parent origin is; if the resource is ever embedded by a context other than the trusted host, those messages leak to it. Exploitability depends on the host embedding model (in a correct MCP Apps host the parent is the trusted host, which limits who can message the frame), so this is a hardening / defense-in-depth issue rather than a directly remotely-triggerable one — hence Low. ## Proof of concept - `poc/verify-no-origin-check.mjs` — static confirmation that the listener has no origin check and outbound uses `'*'`: ``` [x] validates event.origin : NO [x] outgoing postMessage targetOrigin : '*' (any) RESULT: VULNERABLE ``` - `poc/parent-spoof-poc.html` — a page that embeds the UI and injects fabricated rows cross-origin with no handshake; the UI renders them. ## Remediation - Validate `event.origin` against the expected host origin on every inbound message; drop messages from other origins. - Send outbound `postMessage` with an explicit target origin (the host origin established at initialize time) instead of `'*'`. - Optionally, bind to a nonce/channel established during `ui/initialize` so only the negotiated host can drive the panel.

Source published

16 Oct 2026 19:23:48 UTC

Source modified

16 Oct 2026 19:30:03 UTC

Observed here

24 Oct 2026 13:17:17 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · GitHub Advisory Database · CC-BY-4.0. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS_V3 · CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:N/A:N

Publisher rating · LOW