CVE-2026-76894: ckan-mcp-server DataStore Table UI Lacks postMessage Origin Validation
Summary
CVE-2026-76894: The MCP Apps UI resource (an interactive DataStore table rendered in the host's webview/iframe) communicates with its parent via postMessage. Affects @aborruso/ckan-mcp-server versions < 0.4.112. Fixed in 0.4.112. How to fix ↓
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Background
The ckan-mcp-server is an open-source server that facilitates the management of CKAN (Comprehensive Knowledge Archive Network) instances. It provides a user interface for interacting with DataStore tables, allowing users to view and manipulate data stored in these tables. This package is crucial for applications that require data management and visualization, but it has a vulnerability that can be exploited due to improper handling of cross-origin messaging.
Vulnerability Detail
The vulnerability arises from the MCP Apps UI resource, which communicates with its parent window using the postMessage API. The inbound message listener does not validate the origin of incoming messages, allowing any window or frame to send messages to the UI. Additionally, outbound messages are sent with a target origin of '*', meaning they can be received by any origin. This lack of validation can lead to content spoofing, where an attacker can inject arbitrary data into the UI, disrupting the user experience and potentially leading to phishing attacks. The vulnerability is categorized as low severity, with a CVSS score of 3.1, indicating that while it is not easily exploitable, it poses a risk if the application is embedded in an untrusted context.
How To Fix
Minimum fixed version
0.4.112
This is the first release that contains the fix.
npm install @aborruso/ckan-mcp-server@0.4.112Tip — Not sure which version your app runs? Vulert can match this fix to it. Scan free →
Workaround
As a temporary workaround, you can limit the embedding of the UI to trusted origins only. This can be done by ensuring that the application is not embedded in untrusted contexts. However, this is not a complete solution and should not replace the necessary code fixes.
Conclusion
The ckan-mcp-server vulnerability CVE-2026-76894 poses a risk due to improper handling of cross-origin messaging. It is essential to update to the patched version and implement the recommended code changes to mitigate potential exploitation. Regular monitoring with tools like Vulert can help maintain security in open-source applications.
See every vulnerability recorded for @aborruso/ckan-mcp-server →
FAQ
CVE-2026-76894 is a vulnerability in the ckan-mcp-server package that allows for cross-origin message injection due to lack of origin validation in postMessage communications.
An attacker can exploit this vulnerability by sending crafted messages to the UI, potentially injecting malicious data or disrupting the user experience.
The impacts include content spoofing, user experience interference, and potential leakage of sensitive information through outbound messages.
You can use Vulert, which monitors open-source vulnerabilities in your software. By checking your package-lock.json file, you can determine if your application is affected by this vulnerability.
If an immediate update is not possible, ensure that your application is not embedded in untrusted contexts and consider implementing temporary measures to restrict access.
References
Related vulnerabilities
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