CVE-2026-89489 openrisc: fix arbitrary kernel memory access via or1k_atomic syscall
An unprivileged user can exploit missing pointer checks in the OpenRISC atomic syscall to read/write kernel memory and execute code with kernel privileges.
- 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-2026-89489?
CVE-2026-89489 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:
openrisc: fix arbitrary kernel memory access via or1k_atomic syscall
sys_or1k_atomic() (syscall 244 in the "or1k" ABI) takes two user pointers, v1 and v2, and swaps the words they point to in hand-written assembly.
l.lwz r29,0(r4) l.lwz r27,0(r5) l.sw 0(r4),r27 l.sw 0(r5),r29
The pointers are not checked with access_ok(). The four memory accesses also have no exception table entries.
A caller passes a kernel address as either pointer, and the syscall reads from and writes to it directly.
This gives an unprivileged process a kernel read/write primitive. It overwrites kernel data such as the sys_call_table, gaining code execution in kernel context.
Check both pointers before entering the critical section. Add fixups for the four memory accesses so faults on valid but unmapped user addresses return -EFAULT.
[[email protected]: fix comment style]
Which versions are affected by CVE-2026-89489?
How do I fix CVE-2026-89489?
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-2026-89489 being exploited?
There is no known exploitation of CVE-2026-89489 in the wild and no public exploit code.
Sources
Also known as AZL-100697, BELL-CVE-2026-89489, DEBIAN-CVE-2026-89489, GHSA-9rpr-c8j9-pwgc, UBUNTU-CVE-2026-89489.