CVE-2026-74520 iommu/iommufd: Fix IOPF group ownership UAF
A use-after-free in the Linux kernel IOMMUFD subsystem allows attackers to execute arbitrary code or escalate privileges via crafted IOPF group handling.
- 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-2026-74520?
CVE-2026-74520 is a high-severity use after free vulnerability in Linux, published on 15 Aug 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:
iommu/iommufd: Fix IOPF group ownership UAF
iopf_group_alloc() links each last-page IOPF group into the generic IOPF pending list before invoking the domain fault handler. iommufd_fault_iopf_handler() also queued an accepted group in the IOMMUFD deliver list without removing it from the generic pending list.
When detach or HWPT replacement drops the device's IOPF reference count to zero, an IOMMU driver may call iopf_queue_remove_device(). That function responds to and frees groups through the generic pending list without removing the same groups from IOMMUFD's deliver list or response xarray. A later read, response, or cleanup can then access the freed group and cause a UAF.
Fix this by dequeuing an accepted group from the generic pending list before IOMMUFD queues it for userspace response. Make iopf_group_response() send a response regardless of pending-list membership, so the dequeued group can still be completed by IOMMUFD.
Which versions are affected by CVE-2026-74520?
How do I fix CVE-2026-74520?
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-2026-74520 being exploited?
There is no known exploitation of CVE-2026-74520 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-74520, DEBIAN-CVE-2026-74520, GHSA-9qch-cxwm-9cjc, UBUNTU-CVE-2026-74520.