CVE-2026-42559
⚠️ highSummary
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.
CVSS Score
8.8
High
EPSS Score
0.0
Exploit Probability
Published Date
2026-05-14
First Seen: 2026-05-17
📊 Relative Risk Intelligence
This CVE is High Risk - more severe than 81.1% of all 330,193 vulnerabilities in our database.
#62,466
Top 25% most severe
Severity Percentile
🎯 CISA SSVC Assessment Updated: May 14, 2026
🔍 Exploitation Status
None
No known exploits
⚙️ Automatable
NO
Requires human interaction
💥 Technical Impact
Total
Complete system compromise possible
SSVC data provided by
CISA
Last Modified
2026-05-14
Source
NVD 🔗
CVSS Vector 3.1
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H