CVE-2026-89558

/// Technical description

In the Linux kernel, the following vulnerability has been resolved:

md/raid10: fix still_degraded being inverted in raid10_sync_request()

Commit fe6a19d40ceb ("md/md-bitmap: merge md_bitmap_start_sync() into

bitmap_operations") converted still_degraded from int to bool, but

inverted the assignment in the loop that checks whether the array will

still be degraded after the current device is recovered:

"still_degraded = 1" became "still_degraded = false".

As a result, recovering a device while another mirror is still missing

calls md_bitmap_start_sync() with degraded == false, which clears bitmap

bits that the still-missing device needs. When that device is re-added,

its bitmap-based recovery finds the bits already cleared and skips every

region written while the array was degraded, so it is marked In_sync

while holding stale data: silent corruption.

Reproducer (raid10 near=2, 4 disks, internal bitmap):

- fail and remove one disk of each mirror pair

- write to the degraded array

-

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References