DNS rebinding vulnerability in rmcp Streamable HTTP server transport

Prior to version 1.4.0, the rmcp crate's Streamable HTTP server transport did not validate the incoming Host header. This allowed a malicious public website, via a DNS rebinding attack, to send requests to an MCP server running on the victim's loopback or private-network interface. An attacker wh...

RUSTSEC-2026-0189 DNS rebinding vulnerability in rmcp Streamable HTTP server transport

Prior to version 1.4.0, the rmcp crate's Streamable HTTP server transport did not validate the incoming Host header. This allowed a malicious public website, via a DNS rebinding attack, to send requests to an MCP server running on the victim's loopback or private-network interface. An attacker wh...