CVE-2026-89558

CVE Details

Release Date:	2026-09-11
Impact:	Moderate	What is this?

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 - re-add both disks and let recovery finish - "check" reports mismatch_cnt=262272 after 256 MiB of degraded writes and file contents differ; the second disk's "recovery" completes in milliseconds because everything is skipped The same conversion in raid1 got it right (still_degraded = true). Restore the correct value.

See more information about CVE-2026-89558 from MITRE CVE dictionary and NIST NVD

NOTE: The following CVSS metrics and score provided are preliminary and subject to review.

CVSS v3 metrics

Base Score:	3.4
Vector String:	CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:L/A:L
Version:	3.1
Attack Vector:	Local
Attack Complexity:	Low
Privileges Required:	High
User Interaction:	None
Scope:	Unchanged
Confidentiality Impact:	None
Integrity Impact:	Low
Availability Impact:	Low

Errata information

Platform	Errata	Release Date
Oracle Linux version 9 (kernel-uek)	ELSA-2026-500374	2026-10-07