VulnerabilityPublished 28 Oct 2026

CVE-2026-99171: Linux kernel · ntfs3: free the sbi after a grace period

Affects Linux kernelSource CVE Database V5

Not known to be exploited · fixed in c8b1a4840467930e01f1a9374d991d7a8a2896c1 : update Linux kernel when convenient.

Data as of 28 Oct 2026, 10:58 UTC

Severity

Unrated

Rated by Threat Radar · CVSS not yet scored by NVD

Patch: Available – fixed in c8b1a4840467930e01f1a9374d991d7a8a2896c1, c01b091b06412d3b1b53d8c2925f6de586c8a2fc, 7abecef26a9be8f9de70659a3092250461a52072

Exploitation evidence

Disclosed: evidence found.
CVE published 28 Oct 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade Linux kernel to c8b1a4840467930e01f1a9374d991d7a8a2896c1, c01b091b06412d3b1b53d8c2925f6de586c8a2fc or 7abecef26a9be8f9de70659a3092250461a52072.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected ≥ a3a956c78efaa202b1d75190136671cf6e87bfbe, < c8b1a4840467930e01f1a9374d991d7a8a2896c1	Fixed in c8b1a4840467930e01f1a9374d991d7a8a2896c1
LinuxLinux	Affected ≥ a3a956c78efaa202b1d75190136671cf6e87bfbe, < c01b091b06412d3b1b53d8c2925f6de586c8a2fc	Fixed in c01b091b06412d3b1b53d8c2925f6de586c8a2fc
LinuxLinux	Affected ≥ a3a956c78efaa202b1d75190136671cf6e87bfbe, < 7abecef26a9be8f9de70659a3092250461a52072	Fixed in 7abecef26a9be8f9de70659a3092250461a52072
LinuxLinux	Affected =6.2	Fixed in–

Description

In the Linux kernel, the following vulnerability has been resolved: ntfs3: free the sbi after a grace period If the "nocase" mount option ntfs3 uses custom hash and dentry compare functions. Both access ntfs3 superblock private information in rcu pathwalk. ntfs_put_super() and ntfs3_kill_sb() drop the info without any rcu delay. A lookup that's still inside the filesystem when the last reference to the mount is dropped causes a UAF. With a pathwalk held up in ntfs_d_hash() while the last reference to the mount goes away: BUG: KASAN: slab-use-after-free in ntfs_nls_to_utf16+0x752/0x940 Read of size 8 at addr ff1100010453c850 by task walker/99 Call Trace: <TASK> ntfs_nls_to_utf16+0x752/0x940 ntfs_d_hash+0x22b/0x500 link_path_walk+0x11ad/0x1d30 path_lookupat+0x63/0xb00 filename_lookup+0x1f1/0x5b0 vfs_statx+0xd7/0x3b0 [...] Allocated by task 95: __kmalloc_cache_noprof+0x249/0x560 ntfs_init_fs_context+0x2db/0x5a0 alloc_fs_context+0x52e/0xc70 [...] Freed by task 98: kfree+0x1db/0x5b0 deactivate_locked_super+0x9c/0xf0 cleanup_mnt+0x9f/0x130 task_work_run+0x131/0x250 The bug is currently masked by the grace period in namespace_unlock() for umount(2). Keep the necessary information until the filesystem private info is freed and free it with an rcu delay. ntfs3_free_sbi() now runs from an rcu callback and drops the upcase table via ntfs_put_shared(). So switch s_shared_lock over to spin_lock_bh(). Otherwise the callback can deadlock against a task holding the lock on the same cpu.

References

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