Executive brief
Nhost is an open-source development platform used as an alternative to Firebase. A security vulnerability in its command-line interface (CLI) tool could allow a malicious website to hijack a developer's local credentials. If a developer has specifically configured their environment to listen on a network port and enabled cloud access, an attacker could remotely execute database queries, modify project metadata, or delete tables. This could lead to full unauthorized access to the developer's cloud projects and sensitive customer data.
Technical details
The Nhost CLI Model Context Protocol (MCP) server, prior to version 1.41.0, is vulnerable to a cross-origin attack when two non-default conditions are met: the server is explicitly bound to a network port using the --bind flag, and cloud credentials have been configured via 'nhost mcp config'. The vulnerability stems from the upstream mcp-go library hardcoding permissive CORS headers (Access-Control-Allow-Origin: *) and the server's failure to validate the Content-Type header on JSON-RPC requests. This allows a malicious website visited by the developer to bypass CORS preflight checks by using 'text/plain' and issue privileged requests to the local MCP server. An attacker can then invoke tools like 'graphql-query' or 'manage-graphql' to execute raw SQL or modify Hasura metadata using the developer's local administrative secrets. The issue was addressed in version 1.41.0 by removing the ability to bind the MCP server to a network port, restricting it to stdio only.
Affected products
- Nhost CLI < 1.41.0
Timeline
- 2026-03-26: patched: Fix committed to remove network binding capability.
- 2026-03-26: advisory: Vendor advisory GHSA-6c5x-3h35-vvw2 published.
- 2026-03-31: disclosed: CVE-2026-34200 published.