CVE-2026-89558 Affecting linux-6.12 package, versions <6.12.111-1~deb12u1


Severity

Recommended
low

Based on default assessment until relevant scores are available.

Threat Intelligence

EPSS
0.64% (49th percentile)

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  • Snyk IDSNYK-DEBIAN12-LINUX612-20506895
  • published5 Oct 2026
  • disclosed11 Sept 2026

Introduced: 11 Sep 2026

NewCVE-2026-89558  (opens in a new tab)

How to fix?

Upgrade Debian:12 linux-6.12 to version 6.12.111-1~deb12u1 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream linux-6.12 package and not the linux-6.12 package as distributed by Debian. See How to fix? for Debian:12 relevant fixed versions and status.

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.

CVSS Base Scores

version 3.1