CVE-2026-23361 PCI: dwc: ep: Flush MSI-X write before unmapping its ATU entry

High 7.8 Published 25 Mar 2026 Updated 21 Oct 2026

A race condition in the Linux kernel PCI DWC endpoint driver allows host memory corruption or IOMMU errors when unmapping ATU entries during MSI-X interrupts.

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-2026-23361?

CVE-2026-23361 is a high-severity vulnerability in Linux kernel, published on 25 Mar 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:

PCI: dwc: ep: Flush MSI-X write before unmapping its ATU entry

Endpoint drivers use dw_pcie_ep_raise_msix_irq() to raise an MSI-X interrupt to the host using a writel(), which generates a PCI posted write transaction. There's no completion for posted writes, so the writel() may return before the PCI write completes. dw_pcie_ep_raise_msix_irq() also unmaps the outbound ATU entry used for the PCI write, so the write races with the unmap.

If the PCI write loses the race with the ATU unmap, the write may corrupt host memory or cause IOMMU errors, e.g., these when running fio with a larger queue depth against nvmet-pci-epf:

arm-smmu-v3 fc900000.iommu: 0x0000010000000010 arm-smmu-v3 fc900000.iommu: 0x0000020000000000 arm-smmu-v3 fc900000.iommu: 0x000000090000f040 arm-smmu-v3 fc900000.iommu: 0x0000000000000000 arm-smmu-v3 fc900000.iommu: event: F_TRANSLATION client: 0000:01:00.0 sid: 0x100 ssid: 0x0 iova: 0x90000f040 ipa: 0x0 arm-smmu-v3 fc900000.iommu: unpriv data write s1 "Input address caused fault" stag: 0x0

Flush the write by performing a readl() of the same address to ensure that the write has reached the destination before the ATU entry is unmapped.

The same problem was solved for dw_pcie_ep_raise_msi_irq() in commit 8719c64e76bf ("PCI: dwc: ep: Cache MSI outbound iATU mapping"), but there it was solved by dedicating an outbound iATU only for MSI. We can't do the same for MSI-X because each vector can have a different msg_addr and the msg_addr may be changed while the vector is masked.

[bhelgaas: commit log]

Weakness: CWE-787

Which versions are affected by CVE-2026-23361?

It affects 1 product.

Products include Linux kernel.

How do I fix CVE-2026-23361?

Apply the vendor's patch.

Is CVE-2026-23361 being exploited?

There is no known exploitation of CVE-2026-23361 in the wild and no public exploit code.

All Linux kernel vulnerabilities

Sources

Also known as AZL-80573, BELL-CVE-2026-23361, DEBIAN-CVE-2026-23361, GHSA-7vjw-7j3v-c8gx, ROOT-OS-DEBIAN-11-CVE-2026-23361, ROOT-OS-DEBIAN-12-CVE-2026-23361 and 4 more.