CVE-2026-76894 @aborruso CVE debrief

Who should care

Defenders responsible for systems using the ckan-mcp-server package should assess the exposure of their systems and prioritize verifying the affected versions and applying the fixed version.

Why it matters

The ckan-mcp-server package vulnerability requires defenders to assess exposure, verify affected versions, and apply the fixed version to prevent potential data injection and interference with the MCP UI handshake.

• Defenders need to verify if systems using the ckan-mcp-server package are exposed to potential data injection and interference with the MCP UI handshake.
• The lack of origin validation in postMessage events and broadcasting of JSON-RPC messages without an origin restriction requires verification of compensating controls.
• The vulnerability's impact on the MCP UI handshake and data injection requires assessment of the exposure of systems using the ckan-mcp-server package.

Technical summary

The ckan-mcp-server package has a vulnerability in its DataStore Table UI resource, which does not validate the origin of postMessage events and sends messages to a target origin of '*'. This allows any window or frame that can reach the document to inject data into the table and interfere with the MCP UI handshake. The affected code is located in src/resources/datastore-table-ui.ts. The vulnerability is caused by the lack of origin validation in the postMessage event listener and the broadcasting of JSON-RPC messages without an origin restriction. Defenders should prioritize verifying the affected versions of the ckan-mcp-server package and applying the fixed version 0.4.112. They should also assess the

Defensive priority

Defenders should prioritize verifying the affected versions of the ckan-mcp-server package and applying the fixed version 0.4.112. They should also assess the exposure of their systems and verify if any compensating controls are in place.

Recommended defensive actions

• Verify the affected versions of the ckan-mcp-server package and apply the fixed version 0.4.112
• Assess the exposure of systems using the ckan-mcp-server package
• Verify if any compensating controls are in place to mitigate the vulnerability
• Review compensating controls for exposed systems while remediation is scheduled and verified
• Check relevant monitoring, detection, and logs for exposed assets that need extra review
• Track exceptions, retest remediated assets, and close the item only after evidence is documented
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up

Evidence notes

The vulnerability is caused by the lack of origin validation in the postMessage event listener and the broadcasting of JSON-RPC messages without an origin restriction. The affected code is located in src/resources/datastore-table-ui.ts.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.