CVE-2025-38579

Estado: ModificadaAlta (7.8)—

In the Linux kernel, the following vulnerability has been resolved:

f2fs: fix KMSAN uninit-value in extent_info usage

KMSAN reported a use of uninitialized value in `__is_extent_mergeable()` and `__is_back_mergeable()` via the read extent tree path.

The root cause is that `get_read_extent_info()` only initializes three fields (`fofs`, `blk`, `len`) of `struct extent_info`, leaving the remaining fields uninitialized. This leads to undefined behavior when those fields are accessed later, especially during extent merging.

Fix it by zero-initializing the `extent_info` struct before population.

CVSS

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

Probabilidad de explotación (EPSS)

Probabilidad de explotación en los próximos 30 días: 0.17%
Percentil entre todas las CVEs puntuadas: 6
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.

ExplotaciónT1068 Exploitation for Privilege Escalationprivilege escalation85 %
Impacto principalT1499.004 Application or System Exploitationimpact75 %
Impacto secundarioT1565.001 Stored Data Manipulationimpact60 %

Vulnerabilidad de acceso local (AV:L) sin interacción de usuario (UI:N) con privilegios requeridos (PR:L) que causa fallo de inicialización de memoria en el kernel Linux. Permite escala de privilegios o denegación de servicio mediante manipulación de la estructura extent_info.

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

Threat Intelligence Program Restrict File and Directory Permissions Remote Data Storage Filter Network Traffic Execution Prevention Encrypt Sensitive Information

Tecnologías afectadas (2)

Debian — Debian Linux Linux — Linux Kernel

CWE

CWE-908

Referencias

JSON original (NVD)

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      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nf2fs: fix KMSAN uninit-value in extent_info usage\n\nKMSAN reported a use of uninitialized value in `__is_extent_mergeable()`\n and `__is_back_mergeable()` via the read extent tree path.\n\nThe root cause is that `get_read_extent_info()` only initializes three\nfields (`fofs`, `blk`, `len`) of `struct extent_info`, leaving the\nremaining fields uninitialized. This leads to undefined behavior\nwhen those fields are accessed later, especially during\nextent merging.\n\nFix it by zero-initializing the `extent_info` struct before population."
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      "lang": "es",
      "value": "En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: f2fs: corrección del valor no inicializado de KMSAN en el uso de extent_info. KMSAN informó del uso de un valor no inicializado en `__is_extent_mergeable()` y `__is_back_mergeable()` mediante la ruta de lectura del árbol de extensiones. La causa principal es que `get_read_extent_info()` solo inicializa tres campos (`fofs`, `blk`, `len`) de `struct extent_info`, dejando los campos restantes sin inicializar. Esto provoca un comportamiento indefinido al acceder a dichos campos posteriormente, especialmente durante la fusión de extensiones. Para solucionarlo, inicialice a cero la estructura `extent_info` antes de rellenarla."
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