CVE-2025-38527
Estado: ModificadaAlta (7.8)—
In the Linux kernel, the following vulnerability has been resolved:
smb: client: fix use-after-free in cifs_oplock_break
A race condition can occur in cifs_oplock_break() leading to a use-after-free of the cinode structure when unmounting:
The issue occurs when umount has already released its reference to the superblock. When _cifsFileInfo_put() calls cifs_sb_deactive(), this releases the last reference, triggering the immediate cleanup of all inodes under RCU. However, cifs_oplock_break() continues to access the cinode after this point, resulting in use-after-free.
Fix this by holding an extra reference to the superblock during the entire oplock break operation. This ensures that the superblock and its inodes remain valid until the oplock break completes.
Detalles técnicos trazas, registros y código del informe original
cifs_oplock_break()
_cifsFileInfo_put(cfile)
cifsFileInfo_put_final()
cifs_sb_deactive()
[last ref, start releasing sb]
kill_sb()
kill_anon_super()
generic_shutdown_super()
evict_inodes()
dispose_list()
evict()
destroy_inode()
call_rcu(&inode->i_rcu, i_callback)
spin_lock(&cinode->open_file_lock) <- OK
[later] i_callback()
cifs_free_inode()
kmem_cache_free(cinode)
spin_unlock(&cinode->open_file_lock) <- UAF
cifs_done_oplock_break(cinode) <- UAFCVSS
- 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: 0.41%
- Percentil entre todas las CVEs puntuadas: 34
- 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.
- Explotación
T1068Exploitation for Privilege Escalationprivilege escalation85 % - Impacto principal
T1059Command and Scripting Interpreterexecution75 %
Vulnerabilidad local (AV:L, PR:L) de use-after-free en kernel Linux que permite ejecución de código con privilegios elevados tras obtener acceso local. El CVSS muestra compromiso total (C:H, I:H, 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
Tecnologías afectadas (2)
CWE
- CWE-416
Referencias
- https://git.kernel.org/stable/c/09bce2138a30ef10d8821c8c3f73a4ab7a5726bc
- https://git.kernel.org/stable/c/0a4eec84d4d2c4085d4ed8630fd74e4b39033c1b
- https://git.kernel.org/stable/c/2baaf5bbab2ac474c4f92c10fcb3310f824db995
- https://git.kernel.org/stable/c/4256a483fe58af66a46cbf3dc48ff26e580d3308
- https://git.kernel.org/stable/c/705c79101ccf9edea5a00d761491a03ced314210
- https://git.kernel.org/stable/c/da11bd4b697b393a207f19a2ed7d382a811a3ddc
- https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html
JSON original (NVD)
Mostrar
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"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nsmb: client: fix use-after-free in cifs_oplock_break\n\nA race condition can occur in cifs_oplock_break() leading to a\nuse-after-free of the cinode structure when unmounting:\n\n cifs_oplock_break()\n _cifsFileInfo_put(cfile)\n cifsFileInfo_put_final()\n cifs_sb_deactive()\n [last ref, start releasing sb]\n kill_sb()\n kill_anon_super()\n generic_shutdown_super()\n evict_inodes()\n dispose_list()\n evict()\n destroy_inode()\n call_rcu(&inode->i_rcu, i_callback)\n spin_lock(&cinode->open_file_lock) <- OK\n [later] i_callback()\n cifs_free_inode()\n kmem_cache_free(cinode)\n spin_unlock(&cinode->open_file_lock) <- UAF\n cifs_done_oplock_break(cinode) <- UAF\n\nThe issue occurs when umount has already released its reference to the\nsuperblock. When _cifsFileInfo_put() calls cifs_sb_deactive(), this\nreleases the last reference, triggering the immediate cleanup of all\ninodes under RCU. However, cifs_oplock_break() continues to access the\ncinode after this point, resulting in use-after-free.\n\nFix this by holding an extra reference to the superblock during the\nentire oplock break operation. This ensures that the superblock and\nits inodes remain valid until the oplock break completes."
},
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"lang": "es",
"value": "En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: smb: cliente: corrección duse after free en cifs_oplock_break. Puede producirse una condición de ejecución en cifs_oplock_break() que provoca un use after free de la estructura cinode al desmontar: cifs_oplock_break() _cifsFileInfo_put(cfile) cifsFileInfo_put_final() cifs_sb_deactive() [última referencia, iniciar la liberación de sb] kill_sb() kill_anon_super() generic_shutdown_super() evict_inodes() dispose_list() evict() destroy_inode() call_rcu(&inode->i_rcu, i_callback) spin_lock(&cinode->open_file_lock) <- OK [más tarde] i_callback() cifs_free_inode() kmem_cache_free(cinode) spin_unlock(&cinode->open_file_lock) <- UAF cifs_done_oplock_break(cinode) <- UAF El problema ocurre cuando umount ya ha liberado su referencia al superbloque. Cuando _cifsFileInfo_put() llama a cifs_sb_deactive(), se libera la última referencia, lo que desencadena la limpieza inmediata de todos los inodos bajo RCU. Sin embargo, cifs_oplock_break() continúa accediendo al cinode después de este punto, lo que resulta en un use after free. Para solucionar esto, mantenga una referencia adicional al superbloque durante toda la operación de ruptura del oplock. Esto garantiza que el superbloque y sus inodos sigan siendo válidos hasta que se complete la ruptura del oplock."
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"lastModified": "2026-07-30T06:23:24.183",
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