CVE-2026-64684 RMCP: Custom HTTP headers leak to cross-origin redirect targets

RMCP is an official Rust SDK for the Model Context Protocol. Prior to 2.1.0, the rmcp crate's StreamableHttpClientTransport in crates/rmcp/src/transport/common/reqwest/streamablehttpclient.rs builds its defaulthttpclient with reqwest's automatic redirect policy and applies caller-supplied values...