CVE-2026-31403
Full vulnerability record from the local CVENow database.
Description
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. 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.
Severity
HIGH
CVSS score
7.8
(v3.1)
Vulnerability status
Modified
Source identifier
416baaa9-dc9f-4396-8d5f-8c081fb06d67
Published
2026-04-03 16:16:39.467000
Last modified
2026-10-19 19:17:51.830000
View original CVE JSON
{
"id": "CVE-2026-31403",
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"published": "2026-04-03T16:16:39.467",
"lastModified": "2026-10-19T19:17:51.830",
"vulnStatus": "Modified",
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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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