{"id":"CVE-2026-90326","title":"In the Linux kernel, the following vulnerability has been resolved:\n\nblk-cgroup: fix race between policy activation and blkg destruction\n\nWhen switching an IO scheduler on a block device, blkcg_activate_policy()\nallocates blkg_policy_dat…","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nblk-cgroup: fix race between policy activation and blkg destruction\n\nWhen switching an IO scheduler on a block device, blkcg_activate_policy()\nallocates blkg_policy_dat…","severity":"high","cvss":7.8,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","vendor":"Linux","product":"Linux","affected":["Linux >= 81c1188905f88b77743d1fdeeedfc8cb7b67787d < b5dae1cd0d8368b4338430ff93403df67f0b8bcc","Linux >= bfe46d2efe46c5c952f982e2ca94fe2ec5e58e2a < 083b58373463a6e5ee60ecb135269348f68ad7df","Linux >= f1c006f1c6850c14040f8337753a63119bba39b9 < ac34e655dffa74349d885a43d098115336f53842","Linux >= f1c006f1c6850c14040f8337753a63119bba39b9 < 2cf9f50a38c1839e549a08e22aa35e8d69e2c8fd","Linux >= f1c006f1c6850c14040f8337753a63119bba39b9 < 5313d4d41739b0cb63000747c97bb1217ac45f3e","Linux >= 6.1.16 < 6.1.17","Linux >= 6.2.3 < 6.2.4","Linux 6.3"],"published":"2026-09-17","updated":"2026-09-18","sourceUpdated":"2026-09-18T18:17:54.130","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-90326","references":[{"url":"https://git.kernel.org/stable/c/083b58373463a6e5ee60ecb135269348f68ad7df","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/2cf9f50a38c1839e549a08e22aa35e8d69e2c8fd","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/5313d4d41739b0cb63000747c97bb1217ac45f3e","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/ac34e655dffa74349d885a43d098115336f53842","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/b5dae1cd0d8368b4338430ff93403df67f0b8bcc","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/17c18a0df70c2b89ff7fcd74622f1540e98d00fd"},{"url":"https://git.kernel.org/stable/c/91062e3a9ed251726df4e20ff9a1113f1c8ded59"},{"url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-90326.json"},{"url":"https://access.redhat.com/security/cve/CVE-2026-90326"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2536227"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-90326"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-90326"},{"url":"https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-90326.mbox"},{"url":"https://kernelcve.org/list/?q=CVE-2026-90326"}],"tags":["nvd","cve.org","csaf","vex","red-hat","score-dispute"],"epss":0.00171,"epssPercentile":0.06449,"ingestedAt":"2026-09-17T16:21:47.822Z","cwe":["CWE-416"],"scores":{"nvd":7.8,"vendor":4.7},"slug":"CVE-2026-90326","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nblk-cgroup: fix race between policy activation and blkg destruction\n\nWhen switching an IO scheduler on a block device, blkcg_activate_policy()\nallocates blkg_policy_data (pd) for all blkgs attached to the queue.\nHowever, blkcg_activate_policy() may race with concurrent blkcg deletion,\nleading to use-after-free and memory leak issues.\n\nThe use-after-free occurs in the following race:\n\nT1 (blkcg_activate_policy):\n  - Successfully allocates pd for blkg1 (loop0->queue, blkcgA)\n  - Fails to allocate pd for blkg2 (loop0->queue, blkcgB)\n  - Enters the enomem rollback path to release blkg1 resources\n\nT2 (blkcg deletion):\n  - blkcgA is deleted concurrently\n  - blkg1 is freed via blkg_free_workfn()\n  - blkg1->pd is freed\n\nT1 (continued):\n  - Rollback path accesses blkg1->pd->online after pd is freed\n  - Triggers use-after-free\n\nIn addition, blkg_free_workfn() frees pd before removing the blkg from\nq->blkg_list. This allows blkcg_activate_policy() to allocate a new pd\nfor a blkg that is being destroyed, leaving the newly allocated pd\nunreachable when the blkg is finally freed.\n\nFix these races by extending blkcg_mutex coverage to serialize\nblkcg_activate_policy() rollback and blkg destruction, ensuring pd\nlifecycle is synchronized with blkg list visibility.\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 6, Red Hat Enterprise Linux 9, Red Hat OpenShift Container Platform 4 · no fix planned: Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 9, Red Hat OpenShift Container Platform 4 · updated 2026-10-23 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-90326.json)","depth":"twilight","depthScore":43,"depthScoreParts":{"impact":42.9,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[{"seq":207259,"id":"CVE-2026-90326","ts":1789757339967,"field":"cvss","old":null,"new":"7.8"},{"seq":207258,"id":"CVE-2026-90326","ts":1789757339967,"field":"severity","old":"none","new":"high"}]}