CVE-2026-93239 arm64: mm: Fix the lockless page-table walk in show_pte()
A race condition in the Linux kernel arm64 memory management allows a local attacker to cause a system crash via a lockless page-table walk.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-93239?
CVE-2026-93239 is a vulnerability in Linux, published on 24 Sep 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:
arm64: mm: Fix the lockless page-table walk in show_pte()
show_pte() walks page tables locklessly and can run with interrupts enabled. A concurrent teardown can free a table page while it is being walked. It can also clear a parent entry after show_pte() checked it; the regular pXd_offset() helpers then reread the cleared entry and can derive a bogus lower-level pointer and fault again.
Use the lockless offset helpers with the saved parent entries, as gup_fast() does, and pass the saved PMD to pte_offset_map().
For task page tables, arm64 selects MMU_GATHER_RCU_TABLE_FREE. Disable local interrupts around the walk to hold off RCU-deferred table frees and block the tlb_remove_table_sync_one() IPI until the walk is finished.
Place the IRQ guard after the header print. This does not make the output a consistent snapshot, but prevents the task page-table walk from dereferencing a released table page or deriving a pointer from a different parent value.
Which versions are affected by CVE-2026-93239?
How do I fix CVE-2026-93239?
Apply the vendor's patch.
Is CVE-2026-93239 being exploited?
There is no known exploitation of CVE-2026-93239 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-93239, DEBIAN-CVE-2026-93239, GHSA-5wwm-gpr7-9rm3, UBUNTU-CVE-2026-93239.