CVE-2026-31403

Estado: ModificadaAlta (7.8)—

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

NFSD: Hold net reference for the lifetime of /proc/fs/nfs/exports fd

The /proc/fs/nfs/exports proc entry is created at module init and persists for the module's lifetime. exports_proc_open() captures the caller's current network namespace and stores its svc_export_cache in seq->private, but takes no reference on the namespace. If the namespace is subsequently torn down (e.g. container destruction after the opener does setns() to a different namespace), nfsd_net_exit() calls nfsd_export_shutdown() which frees the cache. Subsequent reads on the still-open fd dereference the freed cache_detail, walking a freed hash table.

Leer descripción completaMostrar menos

Hold a reference on the struct net for the lifetime of the open file descriptor. This prevents nfsd_net_exit() from running -- and thus prevents nfsd_export_shutdown() from freeing the cache -- while any exports fd is open. cache_detail already stores its net pointer (cd->net, set by cache_create_net()), so exports_release() can retrieve it without additional per-file storage.

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: 0.18%
Percentil entre todas las CVEs puntuadas: 7
Fecha de la puntuación: 5/10/2026

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 principalT1059 Command and Scripting Interpreterexecution75 %
Impacto secundarioT1499.004 Application or System Exploitationimpact70 %

AV:L/PR:L/UI:N indica escalada local de privilegios. Use-after-free en kernel permite ejecución arbitraria de código con privilegios elevados (I:H) o DoS (A:H).

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 Threat Intelligence Program Restrict Web-Based Content Privileged Account Management Limit Software Installation Filter Network Traffic

Tecnologías afectadas (1)

Linux — Linux Kernel

CWE

NVD-CWE-noinfo

Referencias

JSON original (NVD)

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      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nNFSD: Hold net reference for the lifetime of /proc/fs/nfs/exports fd\n\nThe /proc/fs/nfs/exports proc entry is created at module init\nand persists for the module's lifetime. exports_proc_open()\ncaptures the caller's current network namespace and stores\nits svc_export_cache in seq->private, but takes no reference\non the namespace. If the namespace is subsequently torn down\n(e.g. container destruction after the opener does setns() to a\ndifferent namespace), nfsd_net_exit() calls nfsd_export_shutdown()\nwhich frees the cache. Subsequent reads on the still-open fd\ndereference the freed cache_detail, walking a freed hash table.\n\nHold a reference on the struct net for the lifetime of the open\nfile descriptor. This prevents nfsd_net_exit() from running --\nand thus prevents nfsd_export_shutdown() from freeing the cache\n-- while any exports fd is open. cache_detail already stores\nits net pointer (cd->net, set by cache_create_net()), so\nexports_release() can retrieve it without additional per-file\nstorage."
    },
    {
      "lang": "es",
      "value": "En el kernel de Linux, la siguiente vulnerabilidad ha sido resuelta:\n\nNFSD: Mantener la referencia de red durante la vida útil del fd /proc/fs/nfs/exports\n\nLa entrada proc /proc/fs/nfs/exports se crea en la inicialización del módulo y persiste durante la vida útil del módulo. exports_proc_open() captura el espacio de nombres de red actual del llamador y almacena su svc_export_cache en seq -> private, pero no toma ninguna referencia sobre el espacio de nombres. Si el espacio de nombres se desmantela posteriormente (p. ej., destrucción del contenedor después de que el abridor haga setns() a un espacio de nombres diferente), nfsd_net_exit() llama a nfsd_export_shutdown() que libera la caché. Lecturas posteriores en el fd aún abierto desreferencian el cache_detail liberado, recorriendo una tabla hash liberada.\n\nMantener una referencia sobre la struct net durante la vida útil del descriptor de archivo abierto. Esto evita que nfsd_net_exit() se ejecute -- y por lo tanto evita que nfsd_export_shutdown() libere la caché -- mientras cualquier fd de exportaciones esté abierto. cache_detail ya almacena su puntero de red (cd -> net, establecido por cache_create_net()), por lo que exports_release() puede recuperarlo sin almacenamiento adicional por archivo."
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