{
  "affected": [
    {
      "ecosystem_specific": {
        "urgency": "not yet assigned"
      },
      "package": {
        "ecosystem": "Debian:12",
        "name": "linux"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "ecosystem_specific": {
        "urgency": "not yet assigned"
      },
      "package": {
        "ecosystem": "Debian:13",
        "name": "linux"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "ecosystem_specific": {
        "urgency": "not yet assigned"
      },
      "package": {
        "ecosystem": "Debian:14",
        "name": "linux"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "details": "In the Linux kernel, the following vulnerability has been resolved:  null_blk: register configfs subsystem after creating default devices  In null_init(), configfs_register_subsystem() currently runs before register_blkdev(), so when null_blk is built as a module, a racing mkdir() + poweron from userspace can reach null_add_dev() while null_major is still 0. __add_disk() then hits WARN_ON(disk-\u003eminors) (major=0 with minors!=0) and fails:  [root@fedora ~]# [ 2366.521436] WARNING: block/genhd.c:476 at __add_disk+0x8a7/0xde0, [ 2366.523552] Modules linked in: null_blk(+) nft_fib_inet nft_fib_ipv4 nft_fib_ipv6 nft_fib [ 2366.529081] CPU: 26 UID: 0 PID: 1600 Comm: sh Not tainted 7.2.0-rc1+ #66 PREEMPT(full) ...... [ 2366.547251] Call Trace: [ 2366.547575]  \u003cTASK\u003e [ 2366.547831]  ? _raw_spin_lock+0x84/0xe0 [ 2366.548260]  add_disk_fwnode+0x114/0x560 [ 2366.548739]  null_add_dev+0x102d/0x1b80 [null_blk] [ 2366.549310]  ? __pfx_null_add_dev+0x10/0x10 [null_blk] [ 2366.549906]  ? mutex_lock+0xde/0x1c0 [ 2366.550361]  ? __pfx_mutex_lock+0x10/0x10 [ 2366.550827]  nullb_device_power_store+0x1e7/0x280 [null_blk] [ 2366.551499]  ? __pfx_nullb_device_power_store+0x10/0x10 [null_blk] [ 2366.552177]  ? __kmalloc_cache_noprof+0x1f5/0x470 [ 2366.552748]  ? configfs_write_iter+0x35c/0x4e0 [ 2366.553242]  configfs_write_iter+0x286/0x4e0 [ 2366.553787]  vfs_write+0x52d/0xd00 [ 2366.554169]  ? __pfx_vfs_write+0x10/0x10 [ 2366.554679]  ? __pfx___css_rstat_updated+0x10/0x10 [ 2366.555196]  ? fdget_pos+0x1cf/0x4c0 [ 2366.555649]  ksys_write+0xfc/0x1d0 ......  Additionally, the err_dev path destroys all devices on nullb_list while configfs is still registered. If a racing mkdir() + poweron puts a user device on the list, null_destroy_dev()-\u003enull_free_dev() kfrees the user device's nullb_device but /sys/kernel/config/nullb/\u003cname\u003e is still reachable. Any userspace access to the item will trigger a UAF.  For simplicity, move configfs_register_subsystem() to the end to solve the problems above.",
  "id": "DEBIAN-CVE-2026-90189",
  "modified": "2026-09-18T04:47:29.001195056Z",
  "published": "2026-09-17T17:17:13.533Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://security-tracker.debian.org/tracker/CVE-2026-90189"
    }
  ],
  "upstream": [
    "CVE-2026-90189"
  ]
}