CVE-2026-89447 iommufd: Avoid locking internal accesses during unmap
A local attacker can trigger a reference leak in the Linux kernel iommufd subsystem, potentially leading to resource exhaustion and 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-2026-89447?
CVE-2026-89447 is a denial of service 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:
iommufd: Avoid locking internal accesses during unmap
iommufd_access_notify_unmap() skips internal accesses because they do not have an external unmap callback to invoke.
However, the current test calls iommufd_lock_obj() before checking whether the access is internal. If iommufd_lock_obj() succeeds, the loop then sees the internal access and continues, bypassing the matching iommufd_put_object() used by the normal unmap path. This leaks the object reference taken by iommufd_lock_obj().
Check for internal accesses first so skipped entries are never locked.
Which versions are affected by CVE-2026-89447?
How do I fix CVE-2026-89447?
Apply the vendor's patch.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-89447 being exploited?
There is no known exploitation of CVE-2026-89447 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-89447, DEBIAN-CVE-2026-89447, GHSA-jq6v-47fj-pp2p, UBUNTU-CVE-2026-89447.