CVE-2026-425598.8HighCWE-346

CVE-2026-42559: RMCP: DNS rebinding vulnerability in rmcp Streamable HTTP server transport

modelcontextprotocol · rust-sdk

Affected: modelcontextprotocol rust-sdk · Exploitation: unlikely (under 1%)

Not in CyberSIXT coverage yet: no article names this CVE. This page shows the public record.

0.3%probability of exploitation in the next 30 days

19th percentile

050100

Higher than 19% of scored CVEs

8.8HighCVSS 3.1

LowMediumHighCrit.

DescriptionCVE.org

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.

Affected products1

From the CVE record. A product or version that is not listed is unknown, not unaffected.

modelcontextprotocol · rust-sdk< 1.4.0

On the Atlas

Every published CVE is on the CyberSIXT Atlas, grouped by weakness, vendor and month.

Open the Atlas

Exploitation: Unlikely (under 1%). EPSS under 1%, or no score yet.
CISA KEV: Not listed
Public check: No public nuclei template
Weakness: Origin Validation Error · Access Control
Vendor: modelcontextprotocol
Published: May 2026
Band: Unlikely (under 1%), May 2026

CoverageNo articles yet

No CyberSIXT article names CVE-2026-42559 yet, so there is no coverage timeline, action brief or change log for it. Everything on this page comes from the public CVE record, CISA KEV, EPSS and the nuclei template index. Search the archive or see the CVEs in the news.