CVE-2026-42559GHSA-FVH2-GM75-J4J7GHSA-89VP-X53W-74FXRUSTSEC-2026-0140RUSTSEC-2026-0189
RMCP: DNS rebinding vulnerability in rmcp Streamable HTTP server transport
- Published
- Last modified
- Where the record stands: published, rejected by its publisher, or superseded by another id.What do these mean? →
- published
- Whether CISA lists it in its Known Exploited Vulnerabilities catalog: proof that attackers are using it.What do these mean? →
- Not listed in CISA KEV
- Fix
- Fixed in 1.4.0, 0.9.13
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- 1 proof of concept on GitHub
CISA's decision points: whether it is exploited, whether attacks can be automated, and how much control an attacker gets. Assessed (SSVC 2.0.3).What do these mean? →
- Exploitation: none
- Automatable: no
- Technical impact: total
Summary
RMCP is an official Rust SDK for the Model Context Protocol. Prior to version 1.4.0, the rmcp crate's Streamable HTTP server transport (crates/rmcp/src/transport/streamable_http_server/) did not validate the incoming Host header. This allowed a malicious public website, via a DNS rebinding attack, to send authenticated requests to an MCP server running on the victim's loopback or private-network interface. This vulnerability is fixed in 1.4.0.
Timeline
- CVE published
- CISA SSVC assessment
Exploitation: none · Automatable: no · Technical impact: total
- Record last updated
Affected versions
- modelcontextprotocol rust-sdk
fixed in 1.4.0
- dynoxide-rscrates.io
From 0.9.3 · fixed in 0.9.13
- dynoxidenpm
From 0.9.3 · fixed in 0.9.13
- rmcpcrates.io
From 0.0.0-0 · fixed in 1.4.0
- rmcpcrates.io
fixed in 1.4.0