# CVE-2026-76894: CKAN MCP Server: DataStore Table UI resource does not validate postMessage origin (in) and posts to targetOrigin "*" (out)

Status: published. Published: 2026-11-03. Updated: 2026-11-09.

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.

## Remediation

- fix: @aborruso/ckan-mcp-server (npm): GitHub reports patched versions 0.4.112. Check the advisory for the affected release branch. (source: GitHub GHSA-vqff-r82h-9crc) — https://github.com/ondata/ckan-mcp-server/security/advisories/GHSA-vqff-r82h-9crc
- fix: @aborruso/ckan-mcp-server (npm): OSV reports a fixed version 0.4.112. Check the advisory for supported release branches. (source: OSV GHSA-vqff-r82h-9crc) — https://github.com/advisories/GHSA-vqff-r82h-9crc

## Affected products and versions

- ondata / ckan-mcp-server: < 0.4.112 (affected). Source: CNA: GitHub_M
-  / @aborruso/ckan-mcp-server (@aborruso/ckan-mcp-server): < 0.4.112 (affected, GitHub advisory range). Source: GitHub GHSA-vqff-r82h-9crc
-  / @aborruso/ckan-mcp-server (@aborruso/ckan-mcp-server): ≥ 0; < 0.4.112 (affected, semver); OSV events: introduced 0; fixed 0.4.112. Source: OSV GHSA-vqff-r82h-9crc

## Severity and prioritization

- CVSS 3.1: 3.1 (low); CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:N/A:N; source: CNA: GitHub_M

- CVSS 3.1: 3.1 (low); CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:N/A:N; source: NVD: security-advisories@github.com

- CISA KEV: No listing in collected sources

- EPSS: 0.20% as of 2026-11-09; percentile 9.40%

- SSVC: exploitation poc; automatable no; technical impact partial; source ADP: CISA-ADP

- Weaknesses: CWE-345, CWE-940

## Exploit evidence

- exploit: https://github.com/ondata/ckan-mcp-server/security/advisories/GHSA-vqff-r82h-9crc (ADP: CISA-ADP)

## References

- https://github.com/ondata/ckan-mcp-server/security/advisories/GHSA-vqff-r82h-9crc (CNA: GitHub_M; x_refsource_CONFIRM)

- https://github.com/ondata/ckan-mcp-server/commit/3b827af72b228d42aa7b0d7dac5347d16af3f4e5 (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/ondata/ckan-mcp-server/releases/tag/v0.4.112 (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/ondata/ckan-mcp-server/security/advisories/GHSA-vqff-r82h-9crc (ADP: CISA-ADP; exploit)

- https://github.com/ondata/ckan-mcp-server/commit/3b827af72b228d42aa7b0d7dac5347d16af3f4e5 (security-advisories@github.com)

- https://github.com/ondata/ckan-mcp-server/releases/tag/v0.4.112 (security-advisories@github.com)

- https://github.com/ondata/ckan-mcp-server/security/advisories/GHSA-vqff-r82h-9crc (security-advisories@github.com)

- https://github.com/ondata/ckan-mcp-server/security/advisories/GHSA-vqff-r82h-9crc (GitHub Security Advisories; advisory)

- https://github.com/advisories/GHSA-vqff-r82h-9crc (OSV / GitHub Security Advisories; advisory)

- https://osv.dev/vulnerability/GHSA-vqff-r82h-9crc (OSV / GitHub Security Advisories; osv)

## Provenance

- CNA: GitHub_M: https://www.cve.org/CVERecord?id=CVE-2026-76894; retrieved 2026-11-09; source updated 2026-11-09

- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-76894; retrieved 2026-11-04; source updated 2026-11-03

- GitHub Security Advisories: https://github.com/ondata/ckan-mcp-server/security/advisories/GHSA-vqff-r82h-9crc; retrieved 2026-11-04; source updated 2026-08-20

- OSV / GitHub Security Advisories: https://osv.dev/vulnerability/GHSA-vqff-r82h-9crc; retrieved 2026-11-03; source updated 2026-10-16

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-76894; retrieved 2026-11-09; source updated Not reported

Revision: 2e814bbce8c5dcd294e6b8156d749e984964ac80fc04f8904125f29db19e6330

Canonical: https://y2.dev/cve/CVE-2026-76894

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