Vulnerability Details CVE-2026-64108
In the Linux kernel, the following vulnerability has been resolved:
cifs: Fix busy dentry used after unmounting
Since commit 340cea84f691c ("cifs: open files should not hold ref on
superblock"), cifs file only holds the dentry ref_cnt, the cifs file
close work(cfile->deferred) could be executed after unmounting, which
will trigger a warning in generic_shutdown_super:
BUG: Dentry 00000000a14a6845{i=c,n=file} still in use (1) [unmount of
cifs cifs]
The detailed processs is:
process A process B kworker
fd = open(PATH)
vfs_open
file->__f_path = *path // dentry->d_lockref.count = 1
cifs_open
cifs_new_fileinfo
cfile->dentry = dget(dentry) // dentry->d_lockref.count = 2
close(fd)
__fput
cifs_close
queue_delayed_work(deferredclose_wq, cfile->deferred)
dput(dentry) // dentry->d_lockref.count = 1
smb2_deferred_work_close
_cifsFileInfo_put
list_del(&cifs_file->flist)
umount
cleanup_mnt
deactivate_super
cifs_kill_sb
cifs_close_all_deferred_files_sb
cifs_close_all_deferred_files
// cannot find cfile, skip _cifsFileInfo_put
kill_anon_super
generic_shutdown_super
shrink_dcache_for_umount
umount_check
WARN ! // dentry->d_lockref.count = 1
cifsFileInfo_put_final
dput(cifs_file->dentry)
// dentry->d_lockref.count = 0
Fix it by flushing 'deferredclose_wq' before calling kill_anon_super.
Fetch a reproducer in https://bugzilla.kernel.org/show_bug.cgi?id=221548.
Exploit prediction scoring system (EPSS) score
EPSS Score 0.001
EPSS Ranking 3.0%
CVSS Severity
CVSS v3 Score 7.8
Products affected by CVE-2026-64108
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cpe:2.3:o:linux:linux_kernel:6.1.167
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cpe:2.3:o:linux:linux_kernel:6.1.168
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cpe:2.3:o:linux:linux_kernel:6.1.169
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cpe:2.3:o:linux:linux_kernel:6.1.170
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cpe:2.3:o:linux:linux_kernel:6.1.171
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cpe:2.3:o:linux:linux_kernel:6.1.173
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cpe:2.3:o:linux:linux_kernel:6.1.174
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cpe:2.3:o:linux:linux_kernel:6.12.78
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cpe:2.3:o:linux:linux_kernel:6.12.80
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cpe:2.3:o:linux:linux_kernel:6.12.81
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cpe:2.3:o:linux:linux_kernel:6.12.82
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cpe:2.3:o:linux:linux_kernel:6.12.83
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cpe:2.3:o:linux:linux_kernel:6.12.84
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cpe:2.3:o:linux:linux_kernel:6.12.85
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cpe:2.3:o:linux:linux_kernel:6.12.86
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cpe:2.3:o:linux:linux_kernel:6.12.87
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cpe:2.3:o:linux:linux_kernel:6.12.88
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cpe:2.3:o:linux:linux_kernel:6.12.89
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cpe:2.3:o:linux:linux_kernel:6.12.90
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cpe:2.3:o:linux:linux_kernel:6.12.91
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cpe:2.3:o:linux:linux_kernel:6.18.20
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cpe:2.3:o:linux:linux_kernel:6.18.21
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cpe:2.3:o:linux:linux_kernel:6.18.22
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cpe:2.3:o:linux:linux_kernel:6.18.23
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cpe:2.3:o:linux:linux_kernel:6.18.24
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cpe:2.3:o:linux:linux_kernel:6.18.25
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cpe:2.3:o:linux:linux_kernel:6.18.26
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cpe:2.3:o:linux:linux_kernel:6.18.27
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cpe:2.3:o:linux:linux_kernel:6.18.28
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cpe:2.3:o:linux:linux_kernel:6.18.29
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cpe:2.3:o:linux:linux_kernel:6.18.30
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cpe:2.3:o:linux:linux_kernel:6.18.31
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cpe:2.3:o:linux:linux_kernel:6.18.32
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cpe:2.3:o:linux:linux_kernel:6.18.33
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cpe:2.3:o:linux:linux_kernel:6.19.10
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cpe:2.3:o:linux:linux_kernel:6.19.11
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cpe:2.3:o:linux:linux_kernel:6.19.12
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cpe:2.3:o:linux:linux_kernel:6.19.13
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cpe:2.3:o:linux:linux_kernel:6.19.14
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cpe:2.3:o:linux:linux_kernel:6.6.130
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cpe:2.3:o:linux:linux_kernel:6.6.131
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cpe:2.3:o:linux:linux_kernel:6.6.133
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cpe:2.3:o:linux:linux_kernel:6.6.134
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cpe:2.3:o:linux:linux_kernel:6.6.135
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cpe:2.3:o:linux:linux_kernel:6.6.136
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cpe:2.3:o:linux:linux_kernel:6.6.137
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cpe:2.3:o:linux:linux_kernel:6.6.138
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cpe:2.3:o:linux:linux_kernel:6.6.139
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cpe:2.3:o:linux:linux_kernel:6.6.140
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cpe:2.3:o:linux:linux_kernel:6.6.141
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cpe:2.3:o:linux:linux_kernel:7.0
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cpe:2.3:o:linux:linux_kernel:7.0.1
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cpe:2.3:o:linux:linux_kernel:7.0.10
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cpe:2.3:o:linux:linux_kernel:7.0.2
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cpe:2.3:o:linux:linux_kernel:7.0.3
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cpe:2.3:o:linux:linux_kernel:7.0.4
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cpe:2.3:o:linux:linux_kernel:7.0.5
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cpe:2.3:o:linux:linux_kernel:7.0.6
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cpe:2.3:o:linux:linux_kernel:7.0.7
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cpe:2.3:o:linux:linux_kernel:7.0.8
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cpe:2.3:o:linux:linux_kernel:7.0.9
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cpe:2.3:o:linux:linux_kernel:7.1