CVE-2026-59971

mysql_mcp_server fails to validate Origin/Host headers when running in SSE/HTTP transport mode: the MCP Python SDK's DNS-rebinding protection is left disabled, no CORS or TrustedHost middleware is configured, all routes are unauthenticated, and the service binds to 0.0.0.0 by default. The flaw is triggered whenever MCP_TRANSPORT=sse is set; the default stdio mode is not affected. An attacker with network access to the service, or a victim browser coerced via DNS rebinding against a locally bound instance, can invoke the execute_sql tool to run fully attacker-controlled SQL without credentials, yielding complete data exfiltration and modification, and, if the MySQL account holds FILE privileges, arbitrary file read/write and potential remote code execution via webshell drop. Any deployment of mysql_mcp_server with SSE transport enabled is affected, including the 25 publicly reachable instances identified by internet-wide scanning. No public proof-of-concept or confirmed in-the-wild exploitation is known, and the issue is not listed in CISA KEV.

What to do: Upgrade to mysql_mcp_server v0.4.2, which enables the SDK's DNS-rebinding protection via TransportSecuritySettings and recommends binding to 127.0.0.1. Until upgraded, avoid setting MCP_TRANSPORT=sse, bind the service to localhost only, and firewall the port from untrusted networks; also review the configured MySQL account's privileges, especially FILE, and audit for unexpected queries.