> CVE-2026-42559 [HIGH]

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PUBLISHED
2026-05-14 15:16
MODIFIED
2026-05-14 15:16
CVSS_SCORE V3
8.8
EPSS (Prob. Exploit)
0.27%
Top 80.8%
DATA SOURCES:
NVD đź”— 2026-05-14 CWE MITRE đź”— 2026-11-01 FIRST EPSS đź”— 2026-11-01 GITHUB đź”— 2026-10-29 OSV đź”— 2026-11-02

> 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.

> AFFECTED_PRODUCTS

ℹ️ Aucun produit affecté n'a encore été publié par NVD pour cette CVE.

> CVSS V3 METRICS

CVSS_VECTOR
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
EXPLOITABILITY
2.8
IMPACT
5.9

> MÉTRIQUES CVSS DÉTAILLÉES

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Métrique Valeur Interprétation
AV (Vecteur d'Attaque)
Attack Vector
Network (N)
Exploit possible à distance via réseau (HTTP, API, etc.)
AC (Complexité d'Attaque)
Attack Complexity
Low (L)
Peu de conditions requises pour exploiter
PR (Privilèges Requis)
Privileges Required
None (N)
Aucune authentification requise
UI (Interaction Utilisateur)
User Interaction
Required (R)
Nécessite une action utilisateur (clic lien, ouverture fichier, etc.)
S (Périmètre)
Scope
Unchanged (U)
Impact reste dans le périmètre du composant compromis
C (Impact Confidentialité)
Confidentiality Impact
High (H)
Divulgation totale d'informations
I (Impact Intégrité)
Integrity Impact
High (H)
Modification totale des données possible
A (Impact Disponibilité)
Availability Impact
High (H)
Interruption totale du service possible

> RÉSUMÉ DES IMPACTS

Confidentialité
High
Divulgation totale d'informations
Intégrité
High
Modification totale des données possible
Disponibilité
High
Interruption totale du service possible

> WEAKNESSES

CWE-346 CWE-350

> CWE DETAILED DESCRIPTIONS

CWE-346: Origin Validation Error - The product does not properly verify that the source of data or communication is valid. | CWE-350: Reliance on Reverse DNS Resolution for a Security-Critical Action - The product performs reverse DNS resolution on an IP address to obtain the hostname and make a security decision, but it does not properly ensure that the IP address is truly associated with the hostname.

> GITHUB SECURITY ADVISORY

GHSA-89vp-x53w-74fx HIGH

rmcp Streamable HTTP server transport has a DNS rebinding vulnerability

AFFECTED PACKAGES:
RUST / rmcp
< 1.4.0
Fixed in: 1.4.0

> OSV (GOOGLE OPEN SOURCE VULNERABILITIES)

RMCP: DNS rebinding vulnerability in rmcp Streamable HTTP server transport

AFFECTED PACKAGES:
Unknown / Unknown
70 versions affected
ALIASES:
GHSA-89vp-x53w-74fx, GHSA-fvh2-gm75-j4j7, RUSTSEC-2026-0140, RUSTSEC-2026-0189

> HISTORIQUE DES MODIFICATIONS

Première apparition
14/05/2026 15:16
Source: NVD
📊 ENRICHISSEMENT 01/06/2026 06:01
CWE
Champ modifié: Description CWE
Ancienne valeur:
N/A
Nouvelle valeur:
CWE-346: Origin Validation Error - The product does not properly verify that the source of data or communication is valid. | CWE-350: Reliance on Reverse DNS Resolution for a Security-Critical Action ...
Total des modifications: 1 Dernière mise à jour: 5 months ago

> REFERENCES

https://github.com/modelcontextprotocol/rust-sdk/commit/8e22aa2de28df5a285eed87c...
https://github.com/modelcontextprotocol/rust-sdk/issues/815
https://github.com/modelcontextprotocol/rust-sdk/issues/822
https://github.com/modelcontextprotocol/rust-sdk/pull/764
https://github.com/modelcontextprotocol/rust-sdk/security/advisories/GHSA-89vp-x...
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