CVE-2026-21259

Estado: AnalizadaAlta (7.8)—

Heap-based buffer overflow in Microsoft Office Excel allows an unauthorized attacker to elevate privileges locally.

CVSS

Versión: 3.1
Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Puntuación base: 7.8

Probabilidad de explotación (EPSS)

Probabilidad de explotación en los próximos 30 días: 0.56%
Percentil entre todas las CVEs puntuadas: 45
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.

ExplotaciónT1203 Exploitation for Client Executionexecution95 %
Impacto principalT1068 Exploitation for Privilege Escalationprivilege escalation90 %
Impacto secundarioT1059 Command and Scripting Interpreterexecution85 %

AV:L + UI:R indica ejecución en cliente (abrir archivo preparado). El desbordamiento de buffer permite escalada de privilegios local (menciona "elevate privileges"), posibilitando ejecución de código con privilegios elevados.

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

Execution Prevention Application Isolation and Sandboxing Exploit Protection Update Software Threat Intelligence Program Restrict Web-Based Content

Tecnologías afectadas (5)

Microsoft — 365 Apps Microsoft — Excel Microsoft — Office Microsoft — Office Long Term Servicing Channel Microsoft — Office Online Server

CWE

CWE-122
CWE-787

Referencias

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21259

JSON original (NVD)

Mostrar

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