CVE-2026-34742

Estado: ModificadaAlta (7.6)—

The Go MCP SDK used Go's standard encoding/json. Prior to version 1.4.0, the Model Context Protocol (MCP) Go SDK does not enable DNS rebinding protection by default for HTTP-based servers. When an HTTP-based MCP server is run on localhost without authentication with StreamableHTTPHandler or SSEHandler, a malicious website could exploit DNS rebinding to bypass same-origin policy restrictions and send requests to the local MCP server. This could allow an attacker to invoke tools or access resources exposed by the MCP server on behalf of the user in those limited circumstances. This issue has been patched in version 1.4.0.

CVSS

Versión: 4.0
Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Puntuación base: 7.6

Probabilidad de explotación (EPSS)

Probabilidad de explotación en los próximos 30 días: 0.66%
Percentil entre todas las CVEs puntuadas: 50
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.

ExplotaciónT1189 Drive-by Compromiseinitial access75 %
Impacto principalT1059 Command and Scripting Interpreterexecution70 %
Impacto secundarioT1005 Data from Local Systemcollection65 %

Vector CVSS con UI:P y AV:N sugiere interacción del usuario, pero el ataque es específicamente DNS rebinding desde sitio malicioso (XSS-like) contra servidor local. Impactos: invocación de herramientas (T1059) y acceso a recursos locales (T1005).

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

Restrict Web-Based Content User Training Privileged Account Management Limit Software Installation Execution Prevention Behavior Prevention on Endpoint

Tecnologías afectadas (1)

Lfprojects — MCP GO SDK

CWE

CWE-1188
CWE-1188

Referencias

JSON original (NVD)

Mostrar

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