CVE-2026-90401 md: remove REQ_NOWAIT support from raid1/10/456
- Exploited in the wild
- Not known
- Fix
- Available
What is CVE-2026-90401?
CVE-2026-90401 is a high-severity vulnerability in Linux, published on 17 Sep 2026.
Official 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.
Which versions are affected by CVE-2026-90401?
How do I fix CVE-2026-90401?
Upgrade to a fixed version.
Is CVE-2026-90401 being exploited?
There is no known exploitation of CVE-2026-90401 in the wild and no public exploit code.
Sources
Also known as AZL-102989, BELL-CVE-2026-90401, DEBIAN-CVE-2026-90401, GHSA-2326-xp24-ffqm, UBUNTU-CVE-2026-90401.