CVE-2025-21919

Estado: ModificadaAlta (7.8)—

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

sched/fair: Fix potential memory corruption in child_cfs_rq_on_list

child_cfs_rq_on_list attempts to convert a 'prev' pointer to a cfs_rq. This 'prev' pointer can originate from struct rq's leaf_cfs_rq_list, making the conversion invalid and potentially leading to memory corruption. Depending on the relative positions of leaf_cfs_rq_list and the task group (tg) pointer within the struct, this can cause a memory fault or access garbage data.

The issue arises in list_add_leaf_cfs_rq, where both cfs_rq->leaf_cfs_rq_list and rq->leaf_cfs_rq_list are added to the same leaf list. Also, rq->tmp_alone_branch can be set to rq->leaf_cfs_rq_list.

Leer descripción completaMostrar menos

This adds a check `if (prev == &rq->leaf_cfs_rq_list)` after the main conditional in child_cfs_rq_on_list. This ensures that the container_of operation will convert a correct cfs_rq struct.

This check is sufficient because only cfs_rqs on the same CPU are added to the list, so verifying the 'prev' pointer against the current rq's list head is enough.

Fixes a potential memory corruption issue that due to current struct layout might not be manifesting as a crash but could lead to unpredictable behavior when the layout changes.

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: 0.23%
Percentil entre todas las CVEs puntuadas: 12
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 %
Impacto secundarioT1565.001 Stored Data Manipulationimpact75 %

Vulnerabilidad local (AV:L/PR:L) que corrompe memoria en el kernel Linux. Permite escalada de privilegios (T1068) con potencial para ejecución de código (T1059) y manipulación de datos críticos del sistema (T1565.001) mediante acceso no autorizado a estructuras kernel.

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 Restrict File and Directory Permissions Privileged Account Management Remote Data Storage

Tecnologías afectadas (1)

Linux — Linux Kernel

CWE

CWE-787
CWE-787

Referencias

JSON original (NVD)

Mostrar

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      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nsched/fair: Fix potential memory corruption in child_cfs_rq_on_list\n\nchild_cfs_rq_on_list attempts to convert a 'prev' pointer to a cfs_rq.\nThis 'prev' pointer can originate from struct rq's leaf_cfs_rq_list,\nmaking the conversion invalid and potentially leading to memory\ncorruption. Depending on the relative positions of leaf_cfs_rq_list and\nthe task group (tg) pointer within the struct, this can cause a memory\nfault or access garbage data.\n\nThe issue arises in list_add_leaf_cfs_rq, where both\ncfs_rq->leaf_cfs_rq_list and rq->leaf_cfs_rq_list are added to the same\nleaf list. Also, rq->tmp_alone_branch can be set to rq->leaf_cfs_rq_list.\n\nThis adds a check `if (prev == &rq->leaf_cfs_rq_list)` after the main\nconditional in child_cfs_rq_on_list. This ensures that the container_of\noperation will convert a correct cfs_rq struct.\n\nThis check is sufficient because only cfs_rqs on the same CPU are added\nto the list, so verifying the 'prev' pointer against the current rq's list\nhead is enough.\n\nFixes a potential memory corruption issue that due to current struct\nlayout might not be manifesting as a crash but could lead to unpredictable\nbehavior when the layout changes."
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      "value": "En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: sched/fair: Se corrige la posible corrupción de memoria en child_cfs_rq_on_list. child_cfs_rq_on_list intenta convertir un puntero 'prev' en un cfs_rq. Este puntero 'prev' puede originarse en leaf_cfs_rq_list de struct rq, invalidando la conversión y potencialmente provocando corrupción de memoria. Dependiendo de las posiciones relativas de leaf_cfs_rq_list y el puntero del grupo de tareas (tg) dentro de la estructura, esto puede causar un fallo de memoria o acceder a datos basura. El problema surge en list_add_leaf_cfs_rq, donde tanto cfs_rq-&gt;leaf_cfs_rq_list como rq-&gt;leaf_cfs_rq_list se añaden a la misma lista de hojas. Además, rq-&gt;tmp_alone_branch puede establecerse en rq-&gt;leaf_cfs_rq_list. Esto añade una comprobación `if (prev == &amp;rq-&gt;leaf_cfs_rq_list)` después de la condición principal en child_cfs_rq_on_list. Esto garantiza que la operación container_of convierta una estructura cfs_rq correcta. Esta comprobación es suficiente porque solo se añaden a la lista las cfs_rqs en la misma CPU, por lo que basta con verificar el puntero `prev` con la cabecera de la lista de la rq actual. Corrige un posible problema de corrupción de memoria que, debido al diseño actual de la estructura, podría no manifestarse como un fallo, pero podría provocar un comportamiento impredecible al cambiar el diseño."
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  "lastModified": "2026-07-14T13:17:26.870",
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