CVE-2026-45945 iommu/vt-d: Fix race condition during PASID entry replacement
A race condition in the Linux kernel's Intel VT-d driver can cause inconsistent IOMMU states, leading to spurious faults and potential 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-2026-45945?
CVE-2026-45945 is a high-severity vulnerability in Linux kernel, published on 27 May 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: Fix race condition during PASID entry replacement
The Intel VT-d PASID table entry is 512 bits (64 bytes). When replacing an active PASID entry (e.g., during domain replacement), the current implementation calculates a new entry on the stack and copies it to the table using a single structure assignment.
struct pasid_entry *pte, new_pte;
pte = intel_pasid_get_entry(dev, pasid); pasid_pte_config_first_level(iommu, &new_pte, ...); *pte = new_pte;
Because the hardware may fetch the 512-bit PASID entry in multiple 128-bit chunks, updating the entire entry while it is active (Present bit set) risks a "torn" read. In this scenario, the IOMMU hardware could observe an inconsistent state — partially new data and partially old data — leading to unpredictable behavior or spurious faults.
Fix this by removing the unsafe "replace" helpers and following the "clear-then-update" flow, which ensures the Present bit is cleared and the required invalidation handshake is completed before the new configuration is applied.
Weakness: CWE-362
Which versions are affected by CVE-2026-45945?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-45945?
Apply the vendor's patch.
Is CVE-2026-45945 being exploited?
There is no known exploitation of CVE-2026-45945 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2026-45945, DEBIAN-CVE-2026-45945, GHSA-3f6r-v6w8-rw99, UBUNTU-CVE-2026-45945.