CVE-2026-90332 PCI: dwc: ep: Flush cached MSI write before unmapping the iATU
A race condition in the Linux kernel PCI DWC endpoint driver may drop or misroute MSI writes during address changes, potentially causing data corruption or denial of service.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-90332?
CVE-2026-90332 is a high-severity vulnerability in Linux, published on 17 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:
PCI: dwc: ep: Flush cached MSI write before unmapping the iATU
The MSI-X path already flushes any posted MSI-X write before tearing down its iATU mapping. That was added by commit c22533c66cca ("PCI: dwc: ep: Flush MSI-X write before unmapping its ATU entry") to make sure the write reaches the Root Complex before the outbound window that translates it disappears.
The MSI path has the same problem but no equivalent flush. When the Endpoint driver caches an MSI target address and later observes that the Root Complex has changed it, dw_pcie_ep_raise_msi_irq() unmaps the existing iATU entry and reprograms it for the new address. Between the last MSI writel() and the unmap there may still be a posted write sitting in the fabric, and unmapping the iATU entry can drop or misroute that write.
Fix this by reading back from the mapped MSI window before the unmap. The readback drains any posted MSI writes through the same iATU entry that mapped them, which is the same logic the MSI-X path uses.
[mani: commit log]
Which versions are affected by CVE-2026-90332?
How do I fix CVE-2026-90332?
Apply the vendor's patch.
Is CVE-2026-90332 being exploited?
There is no known exploitation of CVE-2026-90332 in the wild and no public exploit code.
Sources
Also known as DEBIAN-CVE-2026-90332, GHSA-4589-rc6p-3w23, UBUNTU-CVE-2026-90332.