CVE-2024-50121

Estado: ModificadaAlta (7.8)—

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

nfsd: cancel nfsd_shrinker_work using sync mode in nfs4_state_shutdown_net

In the normal case, when we excute `echo 0 > /proc/fs/nfsd/threads`, the function `nfs4_state_destroy_net` in `nfs4_state_shutdown_net` will release all resources related to the hashed `nfs4_client`. If the `nfsd_client_shrinker` is running concurrently, the `expire_client` function will first unhash this client and then destroy it. This can lead to the following warning. Additionally, numerous use-after-free errors may occur as well.

nfsd_client_shrinker echo 0 > /proc/fs/nfsd/threads

Leer descripción completaMostrar menos

==================================================================== BUG nfsd_file (Not tainted): Objects remaining in nfsd_file on __kmem_cache_shutdown() -------------------------------------------------------------------- CPU: 4 UID: 0 PID: 764 Comm: sh Not tainted 6.12.0-rc3+ #1

==================================================================== BUG nfsd_file_mark (Tainted: G B W ): Objects remaining nfsd_file_mark on __kmem_cache_shutdown() --------------------------------------------------------------------

To resolve this issue, cancel `nfsd_shrinker_work` using synchronous mode in nfs4_state_shutdown_net.

Detalles técnicos trazas, registros y código del informe original

expire_client                nfsd_shutdown_net
  unhash_client                ...
                               nfs4_state_shutdown_net
                                 /* won't wait shrinker exit */
  /*                             cancel_work(&nn->nfsd_shrinker_work)
   * nfsd_file for this          /* won't destroy unhashed client1 */
   * client1 still alive         nfs4_state_destroy_net
   */

                               nfsd_file_cache_shutdown
                                 /* trigger warning */
                                 kmem_cache_destroy(nfsd_file_slab)
                                 kmem_cache_destroy(nfsd_file_mark_slab)
  /* release nfsd_file and mark */
  __destroy_client

 dump_stack_lvl+0x53/0x70
 slab_err+0xb0/0xf0
 __kmem_cache_shutdown+0x15c/0x310
 kmem_cache_destroy+0x66/0x160
 nfsd_file_cache_shutdown+0xac/0x210 [nfsd]
 nfsd_destroy_serv+0x251/0x2a0 [nfsd]
 nfsd_svc+0x125/0x1e0 [nfsd]
 write_threads+0x16a/0x2a0 [nfsd]
 nfsctl_transaction_write+0x74/0xa0 [nfsd]
 vfs_write+0x1a5/0x6d0
 ksys_write+0xc1/0x160
 do_syscall_64+0x5f/0x170
 entry_SYSCALL_64_after_hwframe+0x76/0x7e

 dump_stack_lvl+0x53/0x70
 slab_err+0xb0/0xf0
 __kmem_cache_shutdown+0x15c/0x310
 kmem_cache_destroy+0x66/0x160
 nfsd_file_cache_shutdown+0xc8/0x210 [nfsd]
 nfsd_destroy_serv+0x251/0x2a0 [nfsd]
 nfsd_svc+0x125/0x1e0 [nfsd]
 write_threads+0x16a/0x2a0 [nfsd]
 nfsctl_transaction_write+0x74/0xa0 [nfsd]
 vfs_write+0x1a5/0x6d0
 ksys_write+0xc1/0x160
 do_syscall_64+0x5f/0x170
 entry_SYSCALL_64_after_hwframe+0x76/0x7e

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: 0.24%
Percentil entre todas las CVEs puntuadas: 13
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 escalation75 %
Impacto principalT1059 Command and Scripting Interpreterexecution45 %

Vulnerabilidad de use-after-free (CWE-416) en kernel Linux que requiere privilegios locales (PR:L) para explotar mediante race condition. La pista sugiere T1068 e impacto en ejecución, aunque el texto no documenta explotación práctica activa.

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 Behavior Prevention on Endpoint

Tecnologías afectadas (1)

Linux — Linux Kernel

CWE

CWE-416
CWE-416

Referencias

JSON original (NVD)

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  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnfsd: cancel nfsd_shrinker_work using sync mode in nfs4_state_shutdown_net\n\nIn the normal case, when we excute `echo 0 > /proc/fs/nfsd/threads`, the\nfunction `nfs4_state_destroy_net` in `nfs4_state_shutdown_net` will\nrelease all resources related to the hashed `nfs4_client`. If the\n`nfsd_client_shrinker` is running concurrently, the `expire_client`\nfunction will first unhash this client and then destroy it. This can\nlead to the following warning. Additionally, numerous use-after-free\nerrors may occur as well.\n\nnfsd_client_shrinker         echo 0 > /proc/fs/nfsd/threads\n\nexpire_client                nfsd_shutdown_net\n  unhash_client                ...\n                               nfs4_state_shutdown_net\n                                 /* won't wait shrinker exit */\n  /*                             cancel_work(&nn->nfsd_shrinker_work)\n   * nfsd_file for this          /* won't destroy unhashed client1 */\n   * client1 still alive         nfs4_state_destroy_net\n   */\n\n                               nfsd_file_cache_shutdown\n                                 /* trigger warning */\n                                 kmem_cache_destroy(nfsd_file_slab)\n                                 kmem_cache_destroy(nfsd_file_mark_slab)\n  /* release nfsd_file and mark */\n  __destroy_client\n\n====================================================================\nBUG nfsd_file (Not tainted): Objects remaining in nfsd_file on\n__kmem_cache_shutdown()\n--------------------------------------------------------------------\nCPU: 4 UID: 0 PID: 764 Comm: sh Not tainted 6.12.0-rc3+ #1\n\n dump_stack_lvl+0x53/0x70\n slab_err+0xb0/0xf0\n __kmem_cache_shutdown+0x15c/0x310\n kmem_cache_destroy+0x66/0x160\n nfsd_file_cache_shutdown+0xac/0x210 [nfsd]\n nfsd_destroy_serv+0x251/0x2a0 [nfsd]\n nfsd_svc+0x125/0x1e0 [nfsd]\n write_threads+0x16a/0x2a0 [nfsd]\n nfsctl_transaction_write+0x74/0xa0 [nfsd]\n vfs_write+0x1a5/0x6d0\n ksys_write+0xc1/0x160\n do_syscall_64+0x5f/0x170\n entry_SYSCALL_64_after_hwframe+0x76/0x7e\n\n====================================================================\nBUG nfsd_file_mark (Tainted: G    B   W         ): Objects remaining\nnfsd_file_mark on __kmem_cache_shutdown()\n--------------------------------------------------------------------\n\n dump_stack_lvl+0x53/0x70\n slab_err+0xb0/0xf0\n __kmem_cache_shutdown+0x15c/0x310\n kmem_cache_destroy+0x66/0x160\n nfsd_file_cache_shutdown+0xc8/0x210 [nfsd]\n nfsd_destroy_serv+0x251/0x2a0 [nfsd]\n nfsd_svc+0x125/0x1e0 [nfsd]\n write_threads+0x16a/0x2a0 [nfsd]\n nfsctl_transaction_write+0x74/0xa0 [nfsd]\n vfs_write+0x1a5/0x6d0\n ksys_write+0xc1/0x160\n do_syscall_64+0x5f/0x170\n entry_SYSCALL_64_after_hwframe+0x76/0x7e\n\nTo resolve this issue, cancel `nfsd_shrinker_work` using synchronous\nmode in nfs4_state_shutdown_net."
    },
    {
      "lang": "es",
      "value": "En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: nfsd: cancelar nfsd_shrinker_work usando el modo de sincronización en nfs4_state_shutdown_net. En el caso normal, cuando ejecutamos `echo 0 &gt; /proc/fs/nfsd/threads`, la función `nfs4_state_destroy_net` en `nfs4_state_shutdown_net` liberará todos los recursos relacionados con el `nfs4_client` con hash. Si `nfsd_client_shrinker` se está ejecutando simultáneamente, la función `expire_client` primero deshará el hash de este cliente y luego lo destruirá. Esto puede generar la siguiente advertencia. Además, también pueden ocurrir numerosos errores de use-after-free. nfsd_client_shrinker echo 0 &gt; /proc/fs/nfsd/threads expire_client nfsd_shutdown_net unhash_client ... nfs4_state_shutdown_net /* no esperará a que el reductor salga */ /* cancel_work(&amp;nn-&gt;nfsd_shrinker_work) * nfsd_file para esto /* no destruirá el cliente1 sin hash */ * el cliente1 sigue activo nfs4_state_destroy_net */ nfsd_file_cache_shutdown /* advertencia de activación */ kmem_cache_destroy(nfsd_file_slab) kmem_cache_destroy(nfsd_file_mark_slab) /* liberar nfsd_file y marcar */ __destroy_client ============================================================================ ERROR nfsd_file (no contaminado): objetos restantes en nfsd_file en __kmem_cache_shutdown() -------------------------------------------------------------------- CPU: 4 UID: 0 PID: 764 Comm: sh No contaminado 6.12.0-rc3+ #1 dump_stack_lvl+0x53/0x70 slab_err+0xb0/0xf0 __kmem_cache_shutdown+0x15c/0x310 kmem_cache_destroy+0x66/0x160 nfsd_file_cache_shutdown+0xac/0x210 [nfsd] nfsd_destroy_serv+0x251/0x2a0 [nfsd] nfsd_svc+0x125/0x1e0 [nfsd] write_threads+0x16a/0x2a0 [nfsd] nfsctl_transaction_write+0x74/0xa0 [nfsd] vfs_write+0x1a5/0x6d0 ksys_write+0xc1/0x160 do_syscall_64+0x5f/0x170 entry_SYSCALL_64_after_hwframe+0x76/0x7e ========================================================================= ERROR nfsd_file_mark (Corrompido: GBW): Objetos que permanecen en nfsd_file_mark en __kmem_cache_shutdown() -------------------------------------------------------------------- dump_stack_lvl+0x53/0x70 slab_err+0xb0/0xf0 __kmem_cache_shutdown+0x15c/0x310 kmem_cache_destroy+0x66/0x160 nfsd_file_cache_shutdown+0xc8/0x210 [nfsd] Para resolver este problema, cancele `nfsd_shrinker_work` usando el modo sincrónico en nfs4_state_shutdown_net."
    }
  ],
  "lastModified": "2026-06-17T08:03:38.553",
  "configurations": [
    {
      "nodes": [
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}