CVE-2025-39866
Estado: ModificadaAlta (7.8)—
In the Linux kernel, the following vulnerability has been resolved:
fs: writeback: fix use-after-free in __mark_inode_dirty()
An use-after-free issue occurred when __mark_inode_dirty() get the bdi_writeback that was in the progress of switching.
Root cause is:
systemd-random-seed kworker ---------------------------------------------------------------------- ___mark_inode_dirty inode_switch_wbs_work_fn
Fix this race condition by holding inode spinlock until wb_wakeup_delayed() finished.
Detalles técnicos trazas, registros y código del informe original
CPU: 1 PID: 562 Comm: systemd-random- Not tainted 6.6.56-gb4403bd46a8e #1
......
pstate: 60400005 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : __mark_inode_dirty+0x124/0x418
lr : __mark_inode_dirty+0x118/0x418
sp : ffffffc08c9dbbc0
........
Call trace:
__mark_inode_dirty+0x124/0x418
generic_update_time+0x4c/0x60
file_modified+0xcc/0xd0
ext4_buffered_write_iter+0x58/0x124
ext4_file_write_iter+0x54/0x704
vfs_write+0x1c0/0x308
ksys_write+0x74/0x10c
__arm64_sys_write+0x1c/0x28
invoke_syscall+0x48/0x114
el0_svc_common.constprop.0+0xc0/0xe0
do_el0_svc+0x1c/0x28
el0_svc+0x40/0xe4
el0t_64_sync_handler+0x120/0x12c
el0t_64_sync+0x194/0x198
spin_lock(&inode->i_lock);
inode_attach_wb
locked_inode_to_wb_and_lock_list
get inode->i_wb
spin_unlock(&inode->i_lock);
spin_lock(&wb->list_lock)
spin_lock(&inode->i_lock)
inode_io_list_move_locked
spin_unlock(&wb->list_lock)
spin_unlock(&inode->i_lock)
spin_lock(&old_wb->list_lock)
inode_do_switch_wbs
spin_lock(&inode->i_lock)
inode->i_wb = new_wb
spin_unlock(&inode->i_lock)
spin_unlock(&old_wb->list_lock)
wb_put_many(old_wb, nr_switched)
cgwb_release
old wb released
wb_wakeup_delayed() accesses wb,
then trigger the use-after-free
issueCVSS
- 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: 0.31%
- Percentil entre todas las CVEs puntuadas: 21
- 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 escalation75 % - Impacto principal
T1499.004Application or System Exploitationimpact65 % - Impacto secundario
T1561.002Disk Structure Wipeimpact50 %
CVE en kernel local (AV:L/PR:L/UI:N), use-after-free que causa corrupción de memoria. Un atacante con permisos podría causar negación de servicio o corrupción de datos del filesystem al explotar la condición de carrera en __mark_inode_dirty().
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/1edc2feb9c759a9883dfe81cb5ed231412d8b2e4
- https://git.kernel.org/stable/c/b187c976111960e6e54a6b1fff724f6e3d39406c
- https://git.kernel.org/stable/c/bf89b1f87c72df79cf76203f71fbf8349cd5c9de
- https://git.kernel.org/stable/c/c8c14adf80bd1a6e4a1d7ee9c2a816881c26d17a
- https://git.kernel.org/stable/c/d02d2c98d25793902f65803ab853b592c7a96b29
- https://git.kernel.org/stable/c/e2a14bbae5d8bacaa301362744a110e2be40a3a3
- https://git.kernel.org/stable/c/e63052921f1b25a836feb1500b841bff7a4a0456
- https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html
- https://cert-portal.siemens.com/productcert/html/ssa-019113.html
- https://cert-portal.siemens.com/productcert/html/ssa-032379.html
- https://cert-portal.siemens.com/productcert/html/ssa-082556.html
JSON original (NVD)
Mostrar
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"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nfs: writeback: fix use-after-free in __mark_inode_dirty()\n\nAn use-after-free issue occurred when __mark_inode_dirty() get the\nbdi_writeback that was in the progress of switching.\n\nCPU: 1 PID: 562 Comm: systemd-random- Not tainted 6.6.56-gb4403bd46a8e #1\n......\npstate: 60400005 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)\npc : __mark_inode_dirty+0x124/0x418\nlr : __mark_inode_dirty+0x118/0x418\nsp : ffffffc08c9dbbc0\n........\nCall trace:\n __mark_inode_dirty+0x124/0x418\n generic_update_time+0x4c/0x60\n file_modified+0xcc/0xd0\n ext4_buffered_write_iter+0x58/0x124\n ext4_file_write_iter+0x54/0x704\n vfs_write+0x1c0/0x308\n ksys_write+0x74/0x10c\n __arm64_sys_write+0x1c/0x28\n invoke_syscall+0x48/0x114\n el0_svc_common.constprop.0+0xc0/0xe0\n do_el0_svc+0x1c/0x28\n el0_svc+0x40/0xe4\n el0t_64_sync_handler+0x120/0x12c\n el0t_64_sync+0x194/0x198\n\nRoot cause is:\n\nsystemd-random-seed kworker\n----------------------------------------------------------------------\n___mark_inode_dirty inode_switch_wbs_work_fn\n\n spin_lock(&inode->i_lock);\n inode_attach_wb\n locked_inode_to_wb_and_lock_list\n get inode->i_wb\n spin_unlock(&inode->i_lock);\n spin_lock(&wb->list_lock)\n spin_lock(&inode->i_lock)\n inode_io_list_move_locked\n spin_unlock(&wb->list_lock)\n spin_unlock(&inode->i_lock)\n spin_lock(&old_wb->list_lock)\n inode_do_switch_wbs\n spin_lock(&inode->i_lock)\n inode->i_wb = new_wb\n spin_unlock(&inode->i_lock)\n spin_unlock(&old_wb->list_lock)\n wb_put_many(old_wb, nr_switched)\n cgwb_release\n old wb released\n wb_wakeup_delayed() accesses wb,\n then trigger the use-after-free\n issue\n\nFix this race condition by holding inode spinlock until\nwb_wakeup_delayed() finished."
}
],
"lastModified": "2026-07-30T06:23:52.687",
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