CVE-2021-34523

Estado: AnalizadaCrítica (9.8)⚠ Explotación activa💥 Exploit

Microsoft Exchange Server Elevation of Privilege Vulnerability

CVSS

Versión: 3.1
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Puntuación base: 9.8

Probabilidad de explotación (EPSS)

Probabilidad de explotación en los próximos 30 días: 100%
Percentil entre todas las CVEs puntuadas: 100
Fecha de la puntuación: 29/9/2026

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).

CISA KEV — explotada activamente

Añadida al catálogo: 3/11/2021
Plazo de remediación: 17/11/2021
Uso conocido en ransomware: Known

💥 Exploits públicos

Hay código de explotación o plantillas de detección públicos. No es lo mismo que explotación activa confirmada (KEV), pero aumenta el riesgo: parchee con prioridad.

Módulo de Metasploit (exploit fiable y al alcance de cualquiera) · Microsoft Exchange ProxyShell RCE
Prueba de concepto en GitHub (no verificada) · Lista de pruebas de concepto en GitHub

⚠️ Las pruebas de concepto de GitHub no están verificadas: algunas son falsas o contienen malware. No las ejecute nunca fuera de un laboratorio aislado.

🎯 Técnicas ATT&CK

Cómo se explota esta vulnerabilidad y qué consigue el atacante, en el lenguaje de MITRE ATT&CK.

ExplotaciónT1190 Exploit Public-Facing Applicationinitial access95 %
Impacto principalT1059 Command and Scripting Interpreterexecution90 %
Impacto secundarioT1078 Valid Accountsstealth · persistence · privilege escalation · initial access85 %
Impacto secundarioT1565.001 Stored Data Manipulationimpact80 %

Vulnerabilidad crítica (CVSS 9.8) en Exchange Server accesible remotamente sin autenticación (AV:N/PR:N) explotada activamente por ransomware. Permite ejecución arbitraria, acceso a cuentas y manipulación de correos.

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

Privileged Account Management Application Developer Guidance Active Directory Configuration Vulnerability Scanning User Training User Account Management

Tecnologías afectadas (1)

Microsoft — Exchange Server

CWE

NVD-CWE-noinfo

Referencias

JSON original (NVD)

Mostrar

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