CVE-2025-39866

See a problem?
Please try reporting it to the source first.
Source
https://cve.org/CVERecord?id=CVE-2025-39866
Import Source
https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2025-39866.json
JSON Data
https://api.osv.dev/v1/vulns/CVE-2025-39866
Downstream
Related
Published
2025-09-19T15:26:35Z
Modified
2026-09-09T03:30:50Z
Severity
  • 7.8 (High) CVSS_V3 - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H CVSS Calculator
Summary
fs: writeback: fix use-after-free in __mark_inode_dirty()
Details

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.

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

Root cause is:

systemd-random-seed kworker

___mark_inode_dirty inode_switch_wbs_work_fn

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 issue

Fix this race condition by holding inode spinlock until wb_wakeup_delayed() finished.

Database specific 
{
    "cna_assigner": "Linux",
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/39xxx/CVE-2025-39866.json"
}
References

Affected packages

Git / git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git

Affected ranges

Type
GIT
Repo
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
Events
Introduced
0747259d13febfcc838980a63c414c9b920cea6f
Fixed
e2a14bbae5d8bacaa301362744a110e2be40a3a3
Fixed
b187c976111960e6e54a6b1fff724f6e3d39406c
Fixed
1edc2feb9c759a9883dfe81cb5ed231412d8b2e4
Fixed
bf89b1f87c72df79cf76203f71fbf8349cd5c9de
Fixed
e63052921f1b25a836feb1500b841bff7a4a0456
Fixed
c8c14adf80bd1a6e4a1d7ee9c2a816881c26d17a
Fixed
d02d2c98d25793902f65803ab853b592c7a96b29

Database specific

source 
"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2025-39866.json"

Linux / Kernel

Package

Name
Kernel

Affected ranges

Type
ECOSYSTEM
Events
Introduced
4.2.0
Fixed
5.10.247
Type
ECOSYSTEM
Events
Introduced
5.11.0
Fixed
5.15.192
Type
ECOSYSTEM
Events
Introduced
5.16.0
Fixed
6.1.151
Type
ECOSYSTEM
Events
Introduced
6.2.0
Fixed
6.6.105
Type
ECOSYSTEM
Events
Introduced
6.7.0
Fixed
6.12.46
Type
ECOSYSTEM
Events
Introduced
6.13.0
Fixed
6.16.6

Database specific

source 
"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2025-39866.json"