CVE-2026-90279 md/raid5: round bitmap stripes with sector division
Incorrect bitmap stripe alignment in Linux kernel RAID5 allows attackers to read or modify unintended disk sectors.
- 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-2026-90279?
CVE-2026-90279 is a 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:
md/raid5: round bitmap stripes with sector division
raid5_bitmap_sector_map() aligns the array range to full RAID5 stripe widths before converting it to component sectors. That width is chunk_sectors multiplied by the number of data disks, and it is not always a power of two.
Reproduce with a 4-disk RAID5, 1024-sector chunks, and three data disks. The full-stripe width is 3072 sectors. For a one-sector write at array sector 3072, correct rounding gives array range [3072, 6144), which maps to component range [1024, 2048). The old round_down()/round_up() logic instead gives [1024, 4096), which maps to [0, 1024).
Use sector_div() based arithmetic so the rounded range is aligned to the actual RAID5 stripe width.
The deterministic mapper test now reports the fixed component range as [1024, 2048), while the old mask-based range was [0, 1024).
Which versions are affected by CVE-2026-90279?
How do I fix CVE-2026-90279?
Apply the vendor's patch.
Is CVE-2026-90279 being exploited?
There is no known exploitation of CVE-2026-90279 in the wild and no public exploit code.
Sources
Also known as AZL-102824, BELL-CVE-2026-90279, DEBIAN-CVE-2026-90279, GHSA-3w3q-m725-w3pg, UBUNTU-CVE-2026-90279.