CVE-2026-48528: Metacat's data repository software can be hacked through SQL attack

Metacat is data repository software that helps researchers preserve, share, and discover data. Metacat versions 2.0.0 through 3.4.0 contain an unauthenticated SQL injection vulnerability in the `/cn/v1/object` and `/cn/v2/object` REST API endpoints due to unsanitized user input that can be passed through to the backend SQL database. The `nodeId` parameter can be modified to inject SQL commands, and the results are returned in error messages. Metacat appends the user-supplied data into the sql query without sanitization or parameterization. This allows extraction of arbitrary data from the underlying PostgresQL database, fully exposing protected information to the attacker. This is accomplished by leveraging the error reporting mechanisms in Metacat, where SQL error responses are mirrored back to the caller in the XML error message returned by Metacat. One approach, for example, is to use the PostgreSQL `CAST` function to generate an error with the results of an arbitrary subquery, which is then injected into the XML error message returned by Metacat. Attackers do not need to be authenticated to execute the attack. In addition, arbitrary SQL statements that insert, update, and delete data in the Metacat database can be executed, resulting in full compromise of all data in the database. Full proof of concept attacks have been developed and verified for these vulnerabilities. The impact of this vulnerability is critical for Metacat deployments in the DataONE network where information from the database can be exfiltrated, added, changed, or deleted. This includes management information about the data catalog, access log information about who accessed data, identifying information about individuals including their ORCID identifier and client IP address, access control information about who should be able to access and modify data, and other critical internals of the data system. This sql injection vulnerability was remediated fully in Metacat version 3.4.1. If upgrading to Metacat 3.4.1 isn't immediately possible, most deployments can mitigate the issue by disabling the `/cn` REST endpoints in the webapp deployment. This API is not needed or used by member repositories in the DataONE network, as it is only used by the DataONE Coordinating Node deployments. Consequently, this API can be disabled without reduction of functionality for most deployments. To disable the vulnerable endpoints, simply remove the servlet and servlet-mapping for the `/cn` endpoints in the servlet engine associated with the two servlets, `edu.ucsb.nceas.metacat.restservice.v1.CNRestServlet` and `edu.ucsb.nceas.metacat.restservice.v2.CNRestServlet`. For example, in Tomcat, remove the relevant `servlet-mapping` elements from the application web.xml file in Metacat.