{"id":"CVE-2026-90189","title":"In the Linux kernel, the following vulnerability has been resolved:\n\nnull_blk: register configfs subsystem after creating default devices\n\nIn null_init(), configfs_register_subsystem() currently runs before\nregister_blkdev(), so when nul…","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nnull_blk: register configfs subsystem after creating default devices\n\nIn null_init(), configfs_register_subsystem() currently runs before\nregister_blkdev(), so when nul…","severity":"medium","vendor":"Linux","product":"Linux","affected":["Linux >= 3bf2bd20734e3e6ffda53719a9c10fb3ee9c5ffa < 2679b11e9256bd70a5ef41783bab6ad6c34a3db1","Linux >= 3bf2bd20734e3e6ffda53719a9c10fb3ee9c5ffa < dbcedbe4819ae21274ea77469e61e46a878b9943","Linux >= 3bf2bd20734e3e6ffda53719a9c10fb3ee9c5ffa < 57debc907aef66319d244009d3370dcd97388d37","Linux >= 3bf2bd20734e3e6ffda53719a9c10fb3ee9c5ffa < d761be1b8f2bbabc41252deb79a426d3f0d4fa10","Linux >= 3bf2bd20734e3e6ffda53719a9c10fb3ee9c5ffa < cab9bf5f68f76cd44e0ec92bd4a60c9b83656a36","Linux >= 3bf2bd20734e3e6ffda53719a9c10fb3ee9c5ffa < c9d293d6bb0575fcb1f3408129453187e2a28a4e","Linux 4.14"],"published":"2026-09-17","updated":"2026-09-17","sourceUpdated":"2026-09-17T17:17:13.533","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-90189","references":[{"url":"https://git.kernel.org/stable/c/2679b11e9256bd70a5ef41783bab6ad6c34a3db1","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/57debc907aef66319d244009d3370dcd97388d37","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/c9d293d6bb0575fcb1f3408129453187e2a28a4e","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/cab9bf5f68f76cd44e0ec92bd4a60c9b83656a36","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/d761be1b8f2bbabc41252deb79a426d3f0d4fa10","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/dbcedbe4819ae21274ea77469e61e46a878b9943","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-90189.json"},{"url":"https://access.redhat.com/security/cve/CVE-2026-90189"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2536420"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-90189"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-90189"},{"url":"https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-90189.mbox"},{"url":"https://kernelcve.org/list/?q=CVE-2026-90189"}],"tags":["nvd","cve.org","csaf","vex","red-hat"],"ingestedAt":"2026-09-17T16:21:47.864Z","epss":0.00173,"epssPercentile":0.06647,"cvss":4.7,"cvssVector":"CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H","cvssSource":"vendor","cwe":["CWE-416"],"slug":"CVE-2026-90189","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nnull_blk: register configfs subsystem after creating default devices\n\nIn null_init(), configfs_register_subsystem() currently runs before\nregister_blkdev(), so when null_blk is built as a module, a racing mkdir()\n+ poweron from userspace can reach null_add_dev() while null_major is still\n0. __add_disk() then hits WARN_ON(disk->minors) (major=0 with minors!=0)\nand fails:\n\n[root@fedora ~]# [ 2366.521436] WARNING: block/genhd.c:476 at __add_disk+0x8a7/0xde0,\n[ 2366.523552] Modules linked in: null_blk(+) nft_fib_inet nft_fib_ipv4 nft_fib_ipv6 nft_fib\n[ 2366.529081] CPU: 26 UID: 0 PID: 1600 Comm: sh Not tainted 7.2.0-rc1+ #66 PREEMPT(full)\n......\n[ 2366.547251] Call Trace:\n[ 2366.547575]  <TASK>\n[ 2366.547831]  ? _raw_spin_lock+0x84/0xe0\n[ 2366.548260]  add_disk_fwnode+0x114/0x560\n[ 2366.548739]  null_add_dev+0x102d/0x1b80 [null_blk]\n[ 2366.549310]  ? __pfx_null_add_dev+0x10/0x10 [null_blk]\n[ 2366.549906]  ? mutex_lock+0xde/0x1c0\n[ 2366.550361]  ? __pfx_mutex_lock+0x10/0x10\n[ 2366.550827]  nullb_device_power_store+0x1e7/0x280 [null_blk]\n[ 2366.551499]  ? __pfx_nullb_device_power_store+0x10/0x10 [null_blk]\n[ 2366.552177]  ? __kmalloc_cache_noprof+0x1f5/0x470\n[ 2366.552748]  ? configfs_write_iter+0x35c/0x4e0\n[ 2366.553242]  configfs_write_iter+0x286/0x4e0\n[ 2366.553787]  vfs_write+0x52d/0xd00\n[ 2366.554169]  ? __pfx_vfs_write+0x10/0x10\n[ 2366.554679]  ? __pfx___css_rstat_updated+0x10/0x10\n[ 2366.555196]  ? fdget_pos+0x1cf/0x4c0\n[ 2366.555649]  ksys_write+0xfc/0x1d0\n......\n\nAdditionally, the err_dev path destroys all devices on nullb_list while\nconfigfs is still registered. If a racing mkdir() + poweron puts a user\ndevice on the list, null_destroy_dev()->null_free_dev() kfrees the user\ndevice's nullb_device but /sys/kernel/config/nullb/<name> is still\nreachable. Any userspace access to the item will trigger a UAF.\n\nFor simplicity, move configfs_register_subsystem() to the end to solve\nthe problems above.\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.\n\n## Vendor advisories\n\n- **Red Hat VEX** · Moderate · affected: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 9, Red Hat OpenShift Container Platform 4 · no fix planned: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 9, Red Hat OpenShift Container Platform 4 · updated 2026-10-21 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-90189.json)","depth":"sunlit","depthScore":26,"depthScoreParts":{"impact":25.9,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[{"seq":227062,"id":"CVE-2026-90189","ts":1792585055109,"field":"cvss","old":null,"new":"4.7"},{"seq":227061,"id":"CVE-2026-90189","ts":1792585055109,"field":"severity","old":"none","new":"medium"}]}