{"cve":"CVE-2026-89558","nvd":{"published":"2026-09-11T20:19:39.540","modified":"2026-10-19T09:17:51.347","status":"Received","description":"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's \"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.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","score":9.8},"cwes":[],"references":["https://git.kernel.org/stable/c/00449d752bee9c8787f42ea1bf533a9fb17f9b6b","https://git.kernel.org/stable/c/0efabe6229dc683dbf6eeebd0f9fddc7971ed420","https://git.kernel.org/stable/c/47f1441b281decde6954a2fa82b4131637d685ac","https://git.kernel.org/stable/c/9bb8da6ecb330a5b1ac9b96f1e55f134a7aef1d4"],"products":[],"source":"nvd","synced_at":"2026-10-19T22:53:43.293028046+00:00"},"epss":{"cve":"CVE-2026-89558","score":0.00635,"percentile":0.50123,"date":"2026-10-25"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}