CVE-2026-64108
cifs: Fix busy dentry used after unmounting
Description
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.
INFO
Published Date :
July 19, 2026, 4:17 p.m.
Last Modified :
July 19, 2026, 4:17 p.m.
Remotely Exploit :
No
Source :
416baaa9-dc9f-4396-8d5f-8c081fb06d67
Affected Products
The following products are affected by CVE-2026-64108
vulnerability.
Even if cvefeed.io is aware of the exact versions of the
products
that
are
affected, the information is not represented in the table below.
No affected product recoded yet
Solution
- Flush the deferred close work queue.
- Ensure all file operations complete before unmounting.
- Update the Linux kernel to the fixed version.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-64108.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-64108 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-64108
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-64108 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-64108 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
New CVE Received by 416baaa9-dc9f-4396-8d5f-8c081fb06d67
Jul. 19, 2026
Action Type Old Value New Value Added Affected [{'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '708c276f516d27beaded7f372ac8111cee43926c', 'lessThan': 'c7364cea52531534676b9f7dbc0a477c11f4c050', 'versionType': 'git'}, {'status': 'affected', 'version': '0629a1a187e424373364d681b42b101894bdb548', 'lessThan': 'bdc349a87f1fb02c18c4071858a06542bfea783d', 'versionType': 'git'}, {'status': 'affected', 'version': '0e4b8faaaebe3137bec5723ef2b3cb0437fb38fd', 'lessThan': 'f2deaa2f409a4598eaa10f2a93a676c0632af248', 'versionType': 'git'}, {'status': 'affected', 'version': 'f655467a9973f964b267871e5fef533ad5014494', 'lessThan': '5e7d9d0805e58fa3760894e73115b7a74024fd07', 'versionType': 'git'}, {'status': 'affected', 'version': '340cea84f691c5206561bb2e0147158fe02070be', 'lessThan': 'e1ffa6cf662383f95816eed1b623429d82675e75', 'versionType': 'git'}, {'status': 'affected', 'version': '340cea84f691c5206561bb2e0147158fe02070be', 'lessThan': 'c68337442f03953237a94577beb468ab2662a851', 'versionType': 'git'}, {'status': 'affected', 'version': '30afc6ea72cc6cf7c8d579e79b64232801c38d08', 'versionType': 'git'}, {'status': 'affected', 'version': '6.1.167', 'lessThan': '6.1.175', 'versionType': 'semver'}, {'status': 'affected', 'version': '6.6.130', 'lessThan': '6.6.142', 'versionType': 'semver'}, {'status': 'affected', 'version': '6.12.78', 'lessThan': '6.12.92', 'versionType': 'semver'}, {'status': 'affected', 'version': '6.18.20', 'lessThan': '6.18.34', 'versionType': 'semver'}, {'status': 'affected', 'version': '6.19.10', 'lessThan': '6.20', 'versionType': 'semver'}], 'programFiles': ['fs/smb/client/cifsfs.c'], 'defaultStatus': 'unaffected'}, {'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '7.0'}, {'status': 'unaffected', 'version': '0', 'lessThan': '7.0', 'versionType': 'semver'}, {'status': 'unaffected', 'version': '6.1.175', 'versionType': 'semver', 'lessThanOrEqual': '6.1.*'}, {'status': 'unaffected', 'version': '6.6.142', 'versionType': 'semver', 'lessThanOrEqual': '6.6.*'}, {'status': 'unaffected', 'version': '6.12.92', 'versionType': 'semver', 'lessThanOrEqual': '6.12.*'}, {'status': 'unaffected', 'version': '6.18.34', 'versionType': 'semver', 'lessThanOrEqual': '6.18.*'}, {'status': 'unaffected', 'version': '7.0.11', 'versionType': 'semver', 'lessThanOrEqual': '7.0.*'}, {'status': 'unaffected', 'version': '7.1', 'versionType': 'original_commit_for_fix', 'lessThanOrEqual': '*'}], 'programFiles': ['fs/smb/client/cifsfs.c'], 'defaultStatus': 'affected'}] Added Description 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. Added Reference https://git.kernel.org/stable/c/5e7d9d0805e58fa3760894e73115b7a74024fd07 Added Reference https://git.kernel.org/stable/c/bdc349a87f1fb02c18c4071858a06542bfea783d Added Reference https://git.kernel.org/stable/c/c68337442f03953237a94577beb468ab2662a851 Added Reference https://git.kernel.org/stable/c/c7364cea52531534676b9f7dbc0a477c11f4c050 Added Reference https://git.kernel.org/stable/c/e1ffa6cf662383f95816eed1b623429d82675e75 Added Reference https://git.kernel.org/stable/c/f2deaa2f409a4598eaa10f2a93a676c0632af248