CVE-2026-89500 ring-buffer: Make cpu_buffer::free_page a buffer_data_read_page
A race condition in the Linux kernel ring buffer can cause crashes or memory leaks due to mismatched page orders during resize operations.
- 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-2026-89500?
CVE-2026-89500 is a high-severity memory corruption vulnerability in Linux, published on 11 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:
ring-buffer: Make cpu_buffer::free_page a buffer_data_read_page
Discarding a cached reader page after a concurrent ring buffer resize uses the new global subbuf_order for the free_pages() call. This mismatched order may crashes the kernel or leaks memory because the cached page was allocated under the old size.
Save the actual free_page order alongside the page address to ensure we always refer to the correct value and do not rely on the potentially stalled cpu_buffer->subbuf_order value. The simplest is to make free_page a buffer_data_read_page which already covers exactly what we need: a page address and a page order.
Which versions are affected by CVE-2026-89500?
How do I fix CVE-2026-89500?
Apply the vendor's patch.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2026-89500 being exploited?
There is no known exploitation of CVE-2026-89500 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-89500, DEBIAN-CVE-2026-89500, GHSA-h78f-r23h-v8hg, UBUNTU-CVE-2026-89500.