CVE-2025-39759
Estado: ModificadaAlta (7)—
In the Linux kernel, the following vulnerability has been resolved:
btrfs: qgroup: fix race between quota disable and quota rescan ioctl
There's a race between a task disabling quotas and another running the rescan ioctl that can result in a use-after-free of qgroup records from the fs_info->qgroup_tree rbtree.
This happens as follows:
Fix this by taking fs_info->qgroup_lock at btrfs_free_qgroup_config(). Also at btrfs_qgroup_rescan() don't start the rescan worker if quotas were already disabled.
Detalles técnicos trazas, registros y código del informe original
1) Task A enters btrfs_ioctl_quota_rescan() -> btrfs_qgroup_rescan(); 2) Task B enters btrfs_quota_disable() and calls btrfs_qgroup_wait_for_completion(), which does nothing because at that point fs_info->qgroup_rescan_running is false (it wasn't set yet by task A); 3) Task B calls btrfs_free_qgroup_config() which starts freeing qgroups from fs_info->qgroup_tree without taking the lock fs_info->qgroup_lock; 4) Task A enters qgroup_rescan_zero_tracking() which starts iterating the fs_info->qgroup_tree tree while holding fs_info->qgroup_lock, but task B is freeing qgroup records from that tree without holding the lock, resulting in a use-after-free.
CVSS
- Versión: 3.1
- Vector: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
- Puntuación base: 7
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: 5/10/2026
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 %
Vulnerabilidad de race condition (CWE-362) en kernel Linux que permite escalada de privilegios mediante use-after-free. Requiere acceso local (AV:L) con privilegios limitados (PR:L) para explotar.
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-362
Referencias
- https://git.kernel.org/stable/c/2fd0f5ceb997f90f4332ccbab6c7e907e6b2d0eb
- https://git.kernel.org/stable/c/7cda0fdde5d9890976861421d207870500f9aace
- https://git.kernel.org/stable/c/b172535ccba12f0cf7d23b3b840989de47fc104d
- https://git.kernel.org/stable/c/c38028ce0d0045ca600b6a8345a0ff92bfb47b66
- https://git.kernel.org/stable/c/dd0b28d877b293b1d7f8727a7de08ae36b6b9ef0
- https://git.kernel.org/stable/c/e1249667750399a48cafcf5945761d39fa584edf
- https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html
- https://cert-portal.siemens.com/productcert/html/ssa-032379.html
JSON original (NVD)
Mostrar
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"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbtrfs: qgroup: fix race between quota disable and quota rescan ioctl\n\nThere's a race between a task disabling quotas and another running the\nrescan ioctl that can result in a use-after-free of qgroup records from\nthe fs_info->qgroup_tree rbtree.\n\nThis happens as follows:\n\n1) Task A enters btrfs_ioctl_quota_rescan() -> btrfs_qgroup_rescan();\n\n2) Task B enters btrfs_quota_disable() and calls\n btrfs_qgroup_wait_for_completion(), which does nothing because at that\n point fs_info->qgroup_rescan_running is false (it wasn't set yet by\n task A);\n\n3) Task B calls btrfs_free_qgroup_config() which starts freeing qgroups\n from fs_info->qgroup_tree without taking the lock fs_info->qgroup_lock;\n\n4) Task A enters qgroup_rescan_zero_tracking() which starts iterating\n the fs_info->qgroup_tree tree while holding fs_info->qgroup_lock,\n but task B is freeing qgroup records from that tree without holding\n the lock, resulting in a use-after-free.\n\nFix this by taking fs_info->qgroup_lock at btrfs_free_qgroup_config().\nAlso at btrfs_qgroup_rescan() don't start the rescan worker if quotas\nwere already disabled."
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