CVE-2026-89484 lockd: fix NULL dereference on lockowner allocation failure
A remote attacker can cause a kernel crash via a null pointer dereference in the lockd module when lockowner allocation fails.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-89484?
CVE-2026-89484 is a vulnerability in Linux, published on 11 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
lockd: fix NULL dereference on lockowner allocation failure
nlmclnt_locks_init_private() installs NLM file lock operations even when nlmclnt_find_lockowner() fails to allocate a lockowner. nlmclnt_proc() then returns -ENOMEM, but the VFS still tears down the partially initialized file_lock and calls locks_release_private().
That invokes nlmclnt_locks_release_private(), which dereferences fl->fl_u.nfs_fl.owner and crashes because the owner was never installed.
Clear fl_ops before attempting to initialize the NLM private state, and install the NLM lock operations only after a lockowner has been allocated successfully.
Which versions are affected by CVE-2026-89484?
How do I fix CVE-2026-89484?
Apply the vendor's patch.
Is CVE-2026-89484 being exploited?
There is no known exploitation of CVE-2026-89484 in the wild and no public exploit code.
Sources
Also known as AZL-100778, BELL-CVE-2026-89484, DEBIAN-CVE-2026-89484, GHSA-7hg8-pf72-7jmh, UBUNTU-CVE-2026-89484.