What’s Vulnerable › Vulnerabilities

CVE-2026-90401: md: remove REQ_NOWAIT support from raid1/10/456

• Severity: high (CVSS 7.1 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.2% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-09-17 · updated 2026-10-19

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.

Affected products

• Linux kernel: from 5.15.111 before 5.16; 5.17 — fixed in 5.16, 7.3

How to fix

Upgrade to a fixed version: Linux kernel 5.16, 7.3. Check the vendor advisory for mitigations.

References

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

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