CVE-2026-89445 iommufd: Fix UAF in selftest IOPF reporting
A use-after-free in the Linux kernel iommufd selftest allows attackers to potentially execute code or escalate privileges via race conditions.
- 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-2026-89445?
CVE-2026-89445 is a high-severity use after free 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: Fix UAF in selftest IOPF reporting
IOMMUFD selftest TRIGGER_IOPF borrows an attach handle from group->pasid_array without synchronizing against PASID detach, then a concurrent iommu_report_device_fault() can dereference that borrowed handle's domain pointer after the detach erases the handle and frees the backing struct iommufd_attach_handle. TRIGGER_IOPF then dereferences the freed handle, causing a UAF.
Fix by adding a iopf_rwsem in mock_dev to follow the expected design of a real driver. Hold its read side across the whole iommu_report_device_fault() call, and its write side around every path that attaches, detaches, or replaces a device domain. This can block new reports and drains in-flight reports before an old attach handle or the IOPF fault parameter can be removed. Also take the write side while registering a mock device, since it can invoke the mock driver's default-domain attach callback.
Which versions are affected by CVE-2026-89445?
How do I fix CVE-2026-89445?
Apply the vendor's patch.
Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.
Is CVE-2026-89445 being exploited?
There is no known exploitation of CVE-2026-89445 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-89445, DEBIAN-CVE-2026-89445, GHSA-52p7-c9pg-r5j6, UBUNTU-CVE-2026-89445.