CVE-2026-64591 iommu/vt-d: Avoid WARNING in sva unbind path
A local attacker can trigger a kernel warning and potential denial of service by unbinding an SVA device on Intel IOMMU hardware lacking PRI support.
- 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-2026-64591?
CVE-2026-64591 is a denial of service vulnerability in Linux, published on 6 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/vt-d: Avoid WARNING in sva unbind path
The Intel IOMMU driver allows SVA on devices even if they do not support PCI/PRI. Commit 39c20c4e83b9 ("iommu/vt-d: Only handle IOPF for SVA when PRI is supported") modified the SVA bind path to allow this configuration by skipping IOPF enablement when PRI is missing. However, it failed to update the unbind path.
This creates an imbalance: the unbind path attempts to disable IOPF for a device that never had it enabled, triggering a WARNING in intel_iommu_disable_iopf():
WARNING: drivers/iommu/intel/iommu.c:3475 at intel_iommu_disable_iopf+0x4f/0x90d Call Trace: <TASK> blocking_domain_set_dev_pasid+0x50/0x70 iommu_detach_device_pasid+0x89/0xc0 iommu_sva_unbind_device+0x73/0x150 xe_vm_close_and_put+0x4d2/0x1200 [xe]
Fix this by bypassing IOPF operations for SVA domains on non-PRI hardware in both the bind and unbind paths.
Which versions are affected by CVE-2026-64591?
How do I fix CVE-2026-64591?
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-2026-64591 being exploited?
There is no known exploitation of CVE-2026-64591 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-64591, DEBIAN-CVE-2026-64591, GHSA-xvw3-8q2r-r787, UBUNTU-CVE-2026-64591.