CVE-2026-43127 ntfs3: fix circular locking dependency in run_unpack_ex
A circular locking dependency in the Linux kernel ntfs3 driver can cause a deadlock, leading to a denial of service.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-43127?
CVE-2026-43127 is a medium-severity vulnerability in Linux kernel, published on 6 May 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
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.
Weakness: CWE-667
Which versions are affected by CVE-2026-43127?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-43127?
Apply the vendor's patch.
Is CVE-2026-43127 being exploited?
There is no known exploitation of CVE-2026-43127 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as AZL-85797, BELL-CVE-2026-43127, DEBIAN-CVE-2026-43127, GHSA-pmpx-w3f2-x2vp, ROOT-OS-DEBIAN-11-CVE-2026-43127, ROOT-OS-DEBIAN-12-CVE-2026-43127 and 4 more.