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CVE-2025-21786

Estado: AnalizadaAlta (7.8)—

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

The commit 68f83057b913("workqueue: Reap workers via kthread_stop() and remove detach_completion") adds code to reap the normal workers but mistakenly does not handle the rescuer and also removes the code waiting for the rescuer in put_unbound_pool(), which caused a use-after-free bug reported by Cheung Wall.

To avoid the use-after-free bug, the pool’s reference must be held until the detachment is complete. Therefore, move the code that puts the pwq after detaching the rescuer from the pool.

Detalles técnicos trazas, registros y código del informe original
workqueue: Put the pwq after detaching the rescuer from the pool

CVSS

Probabilidad de explotación (EPSS)

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.

CVE-2025-21786 es un use-after-free local (AV:L, PR:L) en el kernel Linux que permite al atacante ejecutar código arbitrario con privilegios elevados mediante manipulación de la estructura de rescuer en workqueues.

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 PreventionThreat Intelligence ProgramRestrict Web-Based ContentPrivileged Account ManagementLimit Software InstallationBehavior Prevention on Endpoint

Tecnologías afectadas (1)

Linux — Linux Kernel

CWE

Referencias

JSON original (NVD)

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          "options": [
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              "versionType": "semver",
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      "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
      "description": [
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          "value": "CWE-416"
        }
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    }
  ],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nworkqueue: Put the pwq after detaching the rescuer from the pool\n\nThe commit 68f83057b913(\"workqueue: Reap workers via kthread_stop() and\nremove detach_completion\") adds code to reap the normal workers but\nmistakenly does not handle the rescuer and also removes the code waiting\nfor the rescuer in put_unbound_pool(), which caused a use-after-free bug\nreported by Cheung Wall.\n\nTo avoid the use-after-free bug, the pool’s reference must be held until\nthe detachment is complete. Therefore, move the code that puts the pwq\nafter detaching the rescuer from the pool."
    },
    {
      "lang": "es",
      "value": "En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: workqueue: colocar el pwq después de separar el rescatador del grupo el commit 68f83057b913(\"workqueue: Reap workers via kthread_stop() and remove detach_completion\") agrega código para recolectar los trabajadores normales, pero por error no gestiona el rescatador y también elimina el código que espera al rescatador en put_unbound_pool(), lo que causó un error de use after free informado por Cheung Wall. Para evitar el error de use after free, la referencia del grupo debe mantenerse hasta que se complete la separación. Por lo tanto, mueva el código que coloca el pwq después de separar el rescatador del grupo."
    }
  ],
  "lastModified": "2026-06-17T08:44:16.453",
  "configurations": [
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}