Bug 2477475 (CVE-2026-42559) - CVE-2026-42559 rmcp: rmcp: Unauthorized access to MCP server via DNS rebinding vulnerability
Summary: CVE-2026-42559 rmcp: rmcp: Unauthorized access to MCP server via DNS rebindin...
Keywords:
Status: NEW
Alias: CVE-2026-42559
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
high
high
Target Milestone: ---
Assignee: Product Security
QA Contact:
URL:
Whiteboard:
Depends On: 2477786 2477787
Blocks:
TreeView+ depends on / blocked
 
Reported: 2026-05-14 16:02 UTC by OSIDB Bzimport
Modified: 2026-05-15 05:58 UTC (History)
0 users

Fixed In Version:
Clone Of:
Environment:
Last Closed:
Embargoed:

Attachments (Terms of Use)

Description OSIDB Bzimport 2026-05-14 16:02:27 UTC 
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.
Note You need to log in before you can comment on or make changes to this bug.