CVE-2026-63128
RMCP is an official Rust SDK for the Model Context Protocol. Prior to 2.0.0, the rmcp crate's stateful Streamable HTTP server in crates/rmcp/src/transport/streamable_http_server/tower.rs allows an unauthenticated client to send a well-formed JSON-RPC POST that is not an initialization request, or an initialization request with a mismatched protocol header, causing StreamableHttpService::handle_post to call LocalSessionManager.create_session before validating the message.
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An early validation failure returns without removing the inserted LocalSessionHandle from LocalSessionManager.sessions, permanently retaining session and channel state for the server process lifetime. Repeated requests can grow the shared session table without bound, degrade legitimate-client latency through lock contention, exhaust memory, and terminate the server. This issue is fixed in version 2.0.0.
CVSS
- Versión: 3.1
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- Puntuación base: 7.5
Probabilidad de explotación (EPSS)
- Probabilidad de explotación en los próximos 30 días: 0.63%
- Percentil entre todas las CVEs puntuadas: 48
- Fecha de la puntuación: 6/10/2026
EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).
🎯 Técnicas ATT&CK
Cómo se explota esta vulnerabilidad y qué consigue el atacante, en el lenguaje de MITRE ATT&CK.
- Explotación
T1190Exploit Public-Facing Applicationinitial access95 % - Impacto principal
T1499.004Application or System Exploitationimpact90 % - Impacto secundario
T1529System Shutdown/Rebootimpact85 %
Servidor HTTP expuesto sin autenticación (AV:N PR:N) permite enviar solicitudes JSON-RPC malformadas causando fuga de memoria y agotamiento de recursos (CWE-400, CWE-401, CWE-772), resultando en DoS por consumo de recursos e indisponibilidad del servicio.
Inferido por nuestro agente de análisis a partir de la descripción oficial, el vector CVSS y la CWE, y comprobado por un supervisor. Puede contener errores.
🛡️ Mitigaciones ATT&CK que cubren estas técnicas
Tecnologías afectadas (1)
⚠ Inferidas por IA a partir de la descripción — NVD aún no ha analizado esta CVE; no son CPE verificados.
CWE
- CWE-400, CWE-401, CWE-772
Referencias
- https://github.com/modelcontextprotocol/rust-sdk/commit/dfa7fd6f9309deab60bea230b041be9a3fcda846
- https://github.com/modelcontextprotocol/rust-sdk/pull/934
- https://github.com/modelcontextprotocol/rust-sdk/releases/tag/rmcp-v2.0.0
- https://github.com/modelcontextprotocol/rust-sdk/security/advisories/GHSA-9pj6-vhgr-3mwh
- https://github.com/modelcontextprotocol/rust-sdk/security/advisories/GHSA-9pj6-vhgr-3mwh
JSON original (NVD)
Mostrar
{
"id": "CVE-2026-63128",
"cveTags": [],
"metrics": {
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{
"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
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"role": "CISA Coordinator",
"options": [
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},
{
"automatable": "no"
},
{
"technicalImpact": "partial"
}
],
"version": "2.0.3",
"timestamp": "2026-09-16T15:18:04.578514Z"
}
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"baseSeverity": "HIGH",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
"integrityImpact": "NONE",
"userInteraction": "NONE",
"attackComplexity": "LOW",
"availabilityImpact": "HIGH",
"privilegesRequired": "NONE",
"confidentialityImpact": "NONE"
},
"impactScore": 3.6,
"exploitabilityScore": 3.9
}
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"affected": [
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"source": "security-advisories@github.com",
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"published": "2026-09-16T15:17:39.960",
"references": [
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"descriptions": [
{
"lang": "en",
"value": "RMCP is an official Rust SDK for the Model Context Protocol. Prior to 2.0.0, the rmcp crate's stateful Streamable HTTP server in crates/rmcp/src/transport/streamable_http_server/tower.rs allows an unauthenticated client to send a well-formed JSON-RPC POST that is not an initialization request, or an initialization request with a mismatched protocol header, causing StreamableHttpService::handle_post to call LocalSessionManager.create_session before validating the message. An early validation failure returns without removing the inserted LocalSessionHandle from LocalSessionManager.sessions, permanently retaining session and channel state for the server process lifetime. Repeated requests can grow the shared session table without bound, degrade legitimate-client latency through lock contention, exhaust memory, and terminate the server. This issue is fixed in version 2.0.0."
}
],
"lastModified": "2026-09-30T17:51:56.193",
"sourceIdentifier": "security-advisories@github.com"
}