Linux Kernel up to 6.18.15/6.19.5 ntfs3 ntfs_extend_mft deadlock

Summaryinfo

A vulnerability was found in Linux Kernel up to 6.18.15/6.19.5 and classified as critical. This vulnerability affects the function ntfs_extend_mft of the component ntfs3. The manipulation results in deadlock. This vulnerability is identified as CVE-2026-43127. There is not any exploit available. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability classified as critical has been found in Linux Kernel up to 6.18.15/6.19.5. Affected is the function ntfs_extend_mft of the component ntfs3. The manipulation with an unknown input leads to a deadlock vulnerability. CWE is classifying the issue as CWE-833. The product contains multiple threads or executable segments that are waiting for each other to release a necessary lock, resulting in deadlock. This is going to have an impact on availability. CVE summarizes:

In the Linux kernel, the following vulnerability has been resolved: ntfs3: fix circular locking dependency in run_unpack_ex Syzbot reported a circular locking dependency between wnd->rw_lock (sbi->used.bitmap) and ni->file.run_lock. The deadlock scenario: 1. ntfs_extend_mft() takes ni->file.run_lock then wnd->rw_lock. 2. run_unpack_ex() takes wnd->rw_lock then tries to acquire ni->file.run_lock inside ntfs_refresh_zone(). This creates an AB-BA deadlock. Fix this by using down_read_trylock() instead of down_read() when acquiring run_lock in run_unpack_ex(). If the lock is contended, skip ntfs_refresh_zone() - the MFT zone will be refreshed on the next MFT operation. This breaks the circular dependency since we never block waiting for run_lock while holding wnd->rw_lock.

The advisory is available at git.kernel.org. This vulnerability is traded as CVE-2026-43127 since 05/01/2026. The exploitability is told to be difficult. Technical details are known, but there is no available exploit.

Upgrading to version 6.18.16 or 6.19.6 eliminates this vulnerability. Applying the patch b014372b62237521444ee51384549bdf48b79015/b8d22d9d8260b0f4f4d8e2898c98037c9982ea66/08ce2fee1b869ecbfbd94e0eb2630e52203a2e03 is able to eliminate this problem. The bugfix is ready for download at git.kernel.org. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the vulnerability database at CERT Bund (WID-SEC-2026-1405). If you want to get best quality of vulnerability data, you may have to visit VulDB.

Affected

• Debian Linux
• Oracle Linux
• Microsoft Azure Linux
• Open Source Linux Kernel

Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 6.18.0
• 6.18.1
• 6.18.2
• 6.18.3
• 6.18.4
• 6.18.5
• 6.18.6
• 6.18.7
• 6.18.8
• 6.18.9
• 6.18.10
• 6.18.11
• 6.18.12
• 6.18.13
• 6.18.14
• 6.18.15
• 6.19.0
• 6.19.1
• 6.19.2
• 6.19.3
• 6.19.4
• 6.19.5

License

• open-source

Website

• Vendor: https://www.kernel.org/

CPE 2.3info

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CPE 2.2info

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Entryinfo

If you want to get best quality of vulnerability data, you may have to visit VulDB.

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