Goal Reached Thanks to every supporter — we hit 100%!

Goal: 1000 CNY · Raised: 1359 CNY

100%
Buy Us a Coffee

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

Quick assessment

Affected
modelcontextprotocol rust-sdk
Exploitation
Public or AI PoC available; prioritize validation
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

RMCP是Model Context Protocol开源的一个基于Tokio异步运行时的Rust模型上下文协议SDK实现。 RMCP 1.4.0之前版本存在访问控制错误漏洞，该漏洞源于Streamable HTTP服务器传输未验证传入的Host标头，可能导致恶意公共网站通过DNS重新绑定攻击向受害者回环或私有网络接口上运行的MCP服务器发送认证请求。

CVSS 8.8 · High EPSS 0.24% · P14

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application

Affected Version Matrix 1

VendorProduct Version RangeStatus
modelcontextprotocol rust-sdk < 1.4.0 affected
Get alerts for future matching vulnerabilities Log in to subscribe

I. Basic Information for CVE-2026-42559

Vulnerability Information
Have questions about the vulnerability? See if Shenlong's analysis helps!
View Shenlong Deep Dive ↗

Although we use advanced large model technology, its output may still contain inaccurate or outdated information.Shenlong tries to ensure data accuracy, but please verify and judge based on the actual situation.

Vulnerability Title
RMCP: DNS rebinding vulnerability in rmcp Streamable HTTP server transport
Source: CVE Program / CVE List V5
Vulnerability Description
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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
源验证错误
Source: CVE Program / CVE List V5
Vulnerability Title
RMCP 访问控制错误漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
RMCP是Model Context Protocol开源的一个基于Tokio异步运行时的Rust模型上下文协议SDK实现。 RMCP 1.4.0之前版本存在访问控制错误漏洞，该漏洞源于Streamable HTTP服务器传输未验证传入的Host标头，可能导致恶意公共网站通过DNS重新绑定攻击向受害者回环或私有网络接口上运行的MCP服务器发送认证请求。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
modelcontextprotocol rust-sdk < 1.4.0 -

II. Public POCs for CVE-2026-42559

# POC Description Source Link Shenlong Link
AI-Generated POC Premium
Qwen3.6-35B-A3B · 9885 chars
Pro+ exclusive includes:
Vulnerability reproduction recording (real sandbox build + trigger, exclusive)
In-depth vulnerability mechanism
Trigger conditions & impact
Full executable POC code
Exploit chain & mitigation
POC zip download
100+ AI POC generations per month

III. Intelligence Information for CVE-2026-42559

请登录查看更多情报信息。

Patches & Fixes for CVE-2026-42559 (2)

Vendor Advisories for CVE-2026-42559 (2)

Other References for CVE-2026-42559 (1)

Same Patch Batch · modelcontextprotocol · 2026-05-14 · 6 CVEs total

CVE-2026-45781 3.5 LOW MCP Registry: OCI ownership validation fails open on upstream rate limits, allowing attack
CVE-2026-44429 MCP Registry: Stored XSS in catalogue UI via attribute-quote breakout in publisher-control
CVE-2026-44430 MCP Registry: Unauthenticated SSRF: HTTP namespace verification dials 6to4 / NAT64 / site-
CVE-2026-44427 MCP Registry: Open Redirect
CVE-2026-44428 MCP Registry: GitHub OIDC tokens replayable across registry deployments due to shared audi

IV. Related Vulnerabilities

Same product: rust-sdk
Same vendor: modelcontextprotocol
Same weakness: CWE-346

V. Comments for CVE-2026-42559

No comments yet

Leave a comment