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CVE-2026-21509

Estado: AnalizadaAlta (7.8)⚠ Explotación activa

Reliance on untrusted inputs in a security decision in Microsoft Office allows an unauthorized attacker to bypass a security feature locally.

CVSS

Probabilidad de explotación (EPSS)

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

🎯 Técnicas ATT&CK

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

Vector AV:L sin PR, UI:R indica escalada local con interacción del usuario. CWE-807 (untrusted inputs en decisiones de seguridad) permite bypass de protecciones. Confianza alta en T1068; impactos en ejecución, manipulación de datos y acceso de cuenta derivados de bypass de seguridad local.

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

Application Developer GuidanceActive Directory ConfigurationUser TrainingUser Account ManagementRestrict File and Directory PermissionsPrivileged Account Management

Tecnologías afectadas (3)

Microsoft — 365 AppsMicrosoft — OfficeMicrosoft — Office Long Term Servicing Channel

CWE

Referencias

JSON original (NVD)

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  "published": "2026-01-26T18:16:38.540",
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      "tags": [
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    },
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    }
  ],
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  "cisaActionDue": "2026-02-16",
  "cisaExploitAdd": "2026-01-26",
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  "cisaVulnerabilityName": "Microsoft Office Security Feature Bypass Vulnerability"
}