Linux Kernel up to 6.12.111/6.18.54/7.2.8/7.3-rc4 NTFS3 fs/ntfs3 ntfs_create_inode race condition

CVSS Meta Temp Score
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6.2$0-$5k0.00-

Summaryinfo

A vulnerability was found in Linux Kernel up to 6.12.111/6.18.54/7.2.8/7.3-rc4. It has been classified as critical. This affects the function ntfs_create_inode of the file fs/ntfs3 of the component NTFS3. Performing a manipulation results in race condition. This vulnerability is reported as CVE-2026-98539. The attack is possible to be carried out remotely. No exploit exists. Upgrading the affected component is recommended.

Detailsinfo

A vulnerability, which was classified as critical, was found in Linux Kernel up to 6.12.111/6.18.54/7.2.8/7.3-rc4. This affects the function ntfs_create_inode of the file fs/ntfs3 of the component NTFS3. The manipulation with an unknown input leads to a race condition vulnerability. CWE is classifying the issue as CWE-362. The product contains a code sequence that can run concurrently with other code, and the code sequence requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence that is operating concurrently. This is going to have an impact on availability. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: fs/ntfs3: use d_instantiate_new() in ntfs_create_inode() and murder syzbot's "WARNING in do_new_mount" saga ntfs_create_inode() creates a new inode via ntfs_new_inode(). It hashes it with insert_inode_locked() and so it's marked as I_NEW until unlock_new_inode(). ntfs 3 calls d_instantiate() in between though... Since the dentry was already hashed by the lookup before the create any path walk finds it without touching the parent's i_rwsem and so can lock the inode. If the inode is a directory unlock_new_inode() calls lockdep_annotate_inode_mutex_key() and marks i_rwsem with the i_mutex_dir_key class. That resets the count and the owner of a lock somebody else may already hold by now... syzbot has been spamming us with the same godforsaken bug "WARNING in do_new_mount" since 2023. I can't take it anymore so I went looking. Afaict, syzbot's executor chdirs into a freshly mounted ntfs3 image, creates a directory and then mounts some pseudofs on it. Everytime the mkdir() takes longer than syzbot waits mount() runs concurrently: mkdir("./sys") mount(NULL, "./sys", "sysfs") ntfs_create_inode() d_instantiate() user_path_at() finds the dentry do_lock_mount() inode_lock(inode) namespace_lock() unlock_new_inode() lockdep_annotate_inode_mutex_key() init_rwsem(&inode->i_rwsem) unlock_mount() inode_unlock(inode) The mount side then releases a lock that according to the rwsem nobody holds: DEBUG_RWSEMS_WARN_ON((rwsem_owner(sem) != current) && ...): count = 0x0, magic = 0xffff888043a854e8, owner = 0x0, curr 0xffff888000244880, list empty WARNING: CPU: 0 PID: 5346 at kernel/locking/rwsem.c:1368 __up_write Call Trace: inode_unlock include/linux/fs.h:877 [inline] unlock_mount fs/namespace.c:2892 [inline] do_new_mount_fc fs/namespace.c:3828 [inline] do_new_mount+0x777/0xa40 fs/namespace.c:3887 On PREEMPT_RT the same thing shows up as DEBUG_LOCKS_WARN_ON(rt_mutex_owner(lock) != current) WARNING: kernel/locking/rtmutex_common.h:193 at rt_mutex_slowunlock The up_write() underflows the reset count. A following inode_lock() on that directory then never returns. A path walk into the new directory racing with the mkdir() corrupts the lock the same way via inode_lock_shared() in lookup_slow(). Switch to d_instantiate_new() and drop the trailing unlock_new_inode(). All error paths bail out before that point with I_NEW still set and keep using discard_new_inode(). May we never see this fscking bug report again.

The advisory is shared at git.kernel.org. This vulnerability is uniquely identified as CVE-2026-98539 since 09/25/2026. The exploitability is told to be easy. It is possible to initiate the attack remotely. Technical details are known, but no exploit is available. The price for an exploit might be around USD $0-$5k at the moment (estimation calculated on 10/18/2026).

Upgrading to version 6.12.112, 6.18.55, 7.2.9 or 7.3-rc5 eliminates this vulnerability. Applying the patch 6fda7121cb6a8ea6fbd77d0f787f04b8e8b5358e/37ec7353f4ac495b28284b0fcb0e53d21d1b3f3f/1ae2a242c15b03470b1b16289298e597bbe3bb29/1abd643f3783ea8f8e273c18697ff0413aa92dc7 is able to eliminate this problem. The best possible mitigation is suggested to be upgrading to the latest version.

If you want to get the best quality for vulnerability data then you always have to consider VulDB.

Productinfo

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CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 6.5
VulDB Meta Temp Score: 6.2

VulDB Base Score: 6.5
VulDB Temp Score: 6.2
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

AVACAuCIA
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Race condition
CWE: CWE-362
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined
Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kernel 6.12.112/6.18.55/7.2.9/7.3-rc5
Patch: 6fda7121cb6a8ea6fbd77d0f787f04b8e8b5358e/37ec7353f4ac495b28284b0fcb0e53d21d1b3f3f/1ae2a242c15b03470b1b16289298e597bbe3bb29/1abd643f3783ea8f8e273c18697ff0413aa92dc7

Timelineinfo

09/25/2026 CVE reserved
10/18/2026 +23 days Advisory disclosed
10/18/2026 +0 days VulDB entry created
10/18/2026 +0 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2026-98539 (🔒)
GCVE (CVE): GCVE-0-2026-98539
GCVE (VulDB): GCVE-100-421797

Entryinfo

Created: 10/18/2026 17:52
Changes: 10/18/2026 17:52 (60)
Complete: 🔍
Cache ID: 216::103

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