CVE-2026-23234

Estado: AnalizadaAlta (7.8)—

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

f2fs: fix to avoid UAF in f2fs_write_end_io()

As syzbot reported an use-after-free issue in f2fs_write_end_io().

It is caused by below race condition:

In kill_f2fs_super(), we will drop all page caches of f2fs inodes before call free(sbi), it guarantee that all folios should end its writeback, so it should be safe to access sbi before last folio_end_writeback().

Let's relocate ckpt thread wakeup flow before folio_end_writeback() to resolve this issue.

Detalles técnicos trazas, registros y código del informe original

loop device				umount
- worker_thread
 - loop_process_work
  - do_req_filebacked
   - lo_rw_aio
    - lo_rw_aio_complete
     - blk_mq_end_request
      - blk_update_request
       - f2fs_write_end_io
        - dec_page_count
        - folio_end_writeback
					- kill_f2fs_super
					 - kill_block_super
					  - f2fs_put_super
					 : free(sbi)
       : get_pages(, F2FS_WB_CP_DATA)
         accessed sbi which is freed

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: 0.12%
Percentil entre todas las CVEs puntuadas: 2
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 principalT1059 Command and Scripting Interpreterexecution60 %

CWE-416 (use-after-free) en kernel local (AV:L, PR:L) permite escalada de privilegios. Impacto de ejecución de código derivado del acceso a memoria liberada.

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

Referencias

JSON original (NVD)

Mostrar

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      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nf2fs: fix to avoid UAF in f2fs_write_end_io()\n\nAs syzbot reported an use-after-free issue in f2fs_write_end_io().\n\nIt is caused by below race condition:\n\nloop device\t\t\t\tumount\n- worker_thread\n - loop_process_work\n  - do_req_filebacked\n   - lo_rw_aio\n    - lo_rw_aio_complete\n     - blk_mq_end_request\n      - blk_update_request\n       - f2fs_write_end_io\n        - dec_page_count\n        - folio_end_writeback\n\t\t\t\t\t- kill_f2fs_super\n\t\t\t\t\t - kill_block_super\n\t\t\t\t\t  - f2fs_put_super\n\t\t\t\t\t : free(sbi)\n       : get_pages(, F2FS_WB_CP_DATA)\n         accessed sbi which is freed\n\nIn kill_f2fs_super(), we will drop all page caches of f2fs inodes before\ncall free(sbi), it guarantee that all folios should end its writeback, so\nit should be safe to access sbi before last folio_end_writeback().\n\nLet's relocate ckpt thread wakeup flow before folio_end_writeback() to\nresolve this issue."
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      "lang": "es",
      "value": "En el kernel de Linux, la siguiente vulnerabilidad ha sido resuelta:\n\nf2fs: corrección para evitar UAF en f2fs_write_end_io()\n\nComo syzbot informó un problema de uso después de liberación en f2fs_write_end_io().\n\nEs causado por la siguiente condición de carrera:\n\nloop device\t\t\t\tumount\n- worker_thread\n - loop_process_work\n  - do_req_filebacked\n   - lo_rw_aio\n    - lo_rw_aio_complete\n     - blk_mq_end_request\n      - blk_update_request\n       - f2fs_write_end_io\n        - dec_page_count\n        - folio_end_writeback\n\t\t\t\t\t- kill_f2fs_super\n\t\t\t\t\t - kill_block_super\n\t\t\t\t\t  - f2fs_put_super\n\t\t\t\t\t : free(sbi)\n       : get_pages(, F2FS_WB_CP_DATA)\n         accedió a sbi que está liberado\n\nEn kill_f2fs_super(), descartaremos todas las cachés de página de los inodos f2fs antes de llamar a free(sbi), esto garantiza que todos los folios deberían finalizar su writeback, por lo tanto, debería ser seguro acceder a sbi antes del último folio_end_writeback().\n\nReubicaremos el flujo de activación del hilo ckpt antes de folio_end_writeback() para resolver este problema."
    }
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