{
  "cveId": "CVE-2026-89661",
  "url": "https://patchblox.com/security/cve/CVE-2026-89661",
  "summary": "CVE-2026-89661 is fixed in linux on 1 platform by DEBIAN-CVE-2026-89661 (version 7.2.6-1), released September 23, 2026. It is not reported as exploited. Patch Radar priority: Routine.",
  "title": "linux: In the Linux kernel, the following vulnerability has been resolved:  NFSD: Prevent post-shutdown use-after-free in un...",
  "description": "In the Linux kernel, the following vulnerability has been resolved:  NFSD: Prevent post-shutdown use-after-free in unlock_filesystem  Writing a filesystem path to /proc/fs/nfsd/unlock_filesystem runs nfsd4_cancel_copy_by_sb() before nfsd_mutex is held and before the handler confirms that nn-\u003Enfsd_serv is set. Once nfsd has shut down, nfs4_state_destroy_net() has freed nn-\u003Econf_id_hashtbl but left the pointer intact, so the cancel helper iterates freed slab memory as an array of struct list_head and then dereferences a bogus nfs4_client when it takes clp-\u003Easync_lock. A local administrator holding CAP_SYS_ADMIN can reach this use-after-free by stopping the server and then writing to unlock_filesystem; KASAN reports a slab-use-after-free read in nfsd4_cancel_copy_by_sb().  nfsd4_revoke_states() walks the same state tables and for that reason already runs only under nfsd_mutex with nn-\u003Enfsd_serv confirmed present. Move the async COPY cancel into that protected section so every NFSv4 state-table walker on this path observes a running server. Async copies exist only while the server runs, so gating the cancel on nn-\u003Enfsd_serv loses nothing.",
  "published": "2026-09-11T20:19:52Z",
  "severity": "",
  "epss": 0.00198,
  "epssPercentile": 0.09574,
  "priority": "Routine",
  "priorityTier": 4,
  "exploited": false,
  "vendorExploited": false,
  "disclosed": false,
  "fixes": [
    {
      "platform": "linux",
      "product": "linux",
      "release": "Debian 14",
      "fixedVersion": "7.2.6-1",
      "fix": "DEBIAN-CVE-2026-89661",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2026-89661",
      "released": "2026-09-23T19:19:02Z"
    }
  ],
  "noFixYet": [],
  "dataAsOf": "2026-11-08T19:12:23Z",
  "attribution": {
    "text": "Data: Patchblox Patch Radar",
    "url": "https://patchblox.com/security/patch-radar",
    "terms": "https://patchblox.com/security/patch-radar/use-the-data"
  }
}