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Vulnerabilities

Vulnerability · CVE-2026-99171

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

Published Oct 28, 2026 · catalog updated Oct 28, 2026 · Linux Linux

Last checked Nov 6, 2026. A connected source was read within the last 7 days.

Check if you run it

No confirmed exploitation is on record for CVE-2026-99171. EPSS is 0.17%. Act only if a listed version of Linux Linux is installed.

Gaps on this record

  • No version range is stored. A customer cannot check an installed version against this record.
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.

Same product and reporting

Severity
High—
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.17%
Remediation
Not established
Affected products
linux kernel · vendor Linux Linux

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: 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.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • linux kernelversion unspecified
  • vendor Linux Linuxversion unspecified

How to fix CVE-2026-99171

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-99171. EPSS is 0.17%. Act only if a listed version of Linux Linux is installed.

Which versions are affected?

Affected version ranges are not on this record. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

No weakness class is stored. EPSS 0.17%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Oct 28, 2026 · Tenable CVE Database

    Detected

    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 t

  2. Oct 28, 2026 · CVE.org

    Updated

    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 t

Sources

  • BSI CERT-BundGovernment advisoryCVE-2026-99171

    Linux Kernel: Mehrere Schwachstellen ermöglichen nicht spezifizierten Angriff

    wid.cert-bund.de
  • CVE.orgVulnerability recordCVE-2026-99171

    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 nt

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-99171

    30-day exploitation probability 0.17%

    first.org
  • Linux Kernel CVEVendor advisoryCVE-2026-99171

    From: Greg Kroah-Hartman 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 pri

    git.kernel.org
  • Tenable CVE DatabaseVulnerability recordCVE-2026-99171

    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 t

    tenable.com

References

Freshness

Last verified in this catalog Nov 6, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.

  • FIRST EPSSOct 31, 2026
  • BSI CERT-BundOct 30, 2026
  • CVE.orgOct 29, 2026
  • Linux Kernel CVEOct 28, 2026
  • Tenable CVE DatabaseOct 28, 2026