CVE-2026-89558 (GCVE-0-2026-89558)
Vulnerability from cvelistv5
Published
2026-09-11 19:44
Modified
2026-10-19 08:48
Severity ?
9.8 (Critical) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Summary
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.
References
Impacted products
Vendor Product Version
Linux Linux Version: fe6a19d40ceb44281905485f56dda715e3214e0e
Version: fe6a19d40ceb44281905485f56dda715e3214e0e
Version: fe6a19d40ceb44281905485f56dda715e3214e0e
Version: fe6a19d40ceb44281905485f56dda715e3214e0e
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/md/raid10.c"
          ],
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          "vendor": "Linux",
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              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
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              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.109",
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            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.50",
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            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.4",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
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          "nodes": [
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              "cpeMatch": [
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                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.109",
                  "versionStartIncluding": "6.12",
                  "vulnerable": true
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                  "vulnerable": true
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              ],
              "negate": false,
              "operator": "OR"
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          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nmd/raid10: fix still_degraded being inverted in raid10_sync_request()\n\nCommit fe6a19d40ceb (\"md/md-bitmap: merge md_bitmap_start_sync() into\nbitmap_operations\") converted still_degraded from int to bool, but\ninverted the assignment in the loop that checks whether the array will\nstill be degraded after the current device is recovered:\n\"still_degraded = 1\" became \"still_degraded = false\".\n\nAs a result, recovering a device while another mirror is still missing\ncalls md_bitmap_start_sync() with degraded == false, which clears bitmap\nbits that the still-missing device needs.  When that device is re-added,\nits bitmap-based recovery finds the bits already cleared and skips every\nregion written while the array was degraded, so it is marked In_sync\nwhile holding stale data: silent corruption.\n\nReproducer (raid10 near=2, 4 disks, internal bitmap):\n - fail and remove one disk of each mirror pair\n - write to the degraded array\n - re-add both disks and let recovery finish\n - \"check\" reports mismatch_cnt=262272 after 256 MiB of degraded\n   writes and file contents differ; the second disk\u0027s \"recovery\"\n   completes in milliseconds because everything is skipped\n\nThe same conversion in raid1 got it right (still_degraded = true).\nRestore the correct value."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 9.8,
            "baseSeverity": "CRITICAL",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:N - md RAID10 commonly backs NAS/SAN volumes exported over NFS, ksmbd, iSCSI, and NVMe-oF. Remote writes during dual-degraded operation dirty the write-intent bitmap, and after buggy recovery remote reads reach md_submit_bio()-\u003eraid10_read_request()-\u003eread_balance() and are served from the stale In_sync mirror without local shell access.\nAC:L - The inverted still_degraded assignment is deterministic in raid10_sync_request() whenever one member is recovered while another remains missing or Faulty. The documented fail/remove/write/re-add sequence needs no race or attacker-uncontrolled memory layout; write-intent bitmaps on RAID10 are a standard mdadm default, not a rare config.\nPR:N - Client I/O to an exported RAID10 LUN needs no Linux UID or host capability: unauthenticated iSCSI/NVMe-oF and guest NFS/SMB writes reach md_submit_bio() and later read stale mirrors. md ioctls/sysfs fail/re-add use capable(CAP_SYS_ADMIN), but hot-spare recovery and storage-protocol I/O do not, so Privileges Required is None rather than High.\nUI:N - No victim click, mount, or confirmation is required. The attacker or automated storage clients issue ordinary reads and writes; md_check_recovery() and md_start_sync() invoke raid10_sync_request() from hot-spare activation or disk re-add as kernel background work.\nS:U - Silent corruption, stale-data disclosure, and volume unavailability remain inside the host kernel and the md RAID10 array. The bug does not escape a VM, bypass an IOMMU, or otherwise cross a separate security authority.\nC:H - raid10_spare_active() sets In_sync on the re-added member while it still holds stale sectors. read_balance() then returns that disk\u0027s prior contents, including previously freed blocks that the current filesystem layout may assign to other users\u0027 or overwritten files, disclosing unauthorized data.\nI:H - md_bitmap_start_sync() is called with degraded=false, clearing NEEDED bits the still-missing mirror requires. That device is marked In_sync after skipping dirty regions; later read-modify-write of the stale data is mirrored to all copies, permanently corrupting filesystem and user data.\nA:H - Stale filesystem metadata served from the wrongly In_sync mirror drives remount-ro, XFS shutdown, or panic on errors=panic, and skipped bitmap recovery leaves dirty regions unrestored, denying availability of the RAID10 volume and any boot or data filesystems on it."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-19T08:48:51.700Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/9bb8da6ecb330a5b1ac9b96f1e55f134a7aef1d4"
        },
        {
          "url": "https://git.kernel.org/stable/c/0efabe6229dc683dbf6eeebd0f9fddc7971ed420"
        },
        {
          "url": "https://git.kernel.org/stable/c/00449d752bee9c8787f42ea1bf533a9fb17f9b6b"
        },
        {
          "url": "https://git.kernel.org/stable/c/47f1441b281decde6954a2fa82b4131637d685ac"
        }
      ],
      "title": "md/raid10: fix still_degraded being inverted in raid10_sync_request()",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-89558",
    "datePublished": "2026-09-11T19:44:30.588Z",
    "dateReserved": "2026-09-11T19:38:34.724Z",
    "dateUpdated": "2026-10-19T08:48:51.700Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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