{"api_version":"1","generated_at":"2026-09-19T10:09:07+00:00","cve":"CVE-2026-90326","urls":{"html":"https://cve.report/CVE-2026-90326","api":"https://cve.report/api/cve/CVE-2026-90326.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-90326","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-90326"},"summary":{"title":"blk-cgroup: fix race between policy activation and blkg destruction","description":"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_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.","state":"PUBLISHED","assigner":"Linux","published_at":"2026-09-17 17:17:30","updated_at":"2026-09-18 18:17:54"},"problem_types":[],"metrics":[{"version":"3.1","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","type":"Secondary","score":"7.8","severity":"HIGH","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","data":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","baseScore":7.8,"baseSeverity":"HIGH","attackVector":"LOCAL","attackComplexity":"LOW","privilegesRequired":"LOW","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"HIGH"}},{"version":"3.1","source":"CNA","type":"DECLARED","score":"7.8","severity":"HIGH","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","data":{"baseScore":7.8,"baseSeverity":"HIGH","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","version":"3.1"}}],"references":[{"url":"https://git.kernel.org/stable/c/5313d4d41739b0cb63000747c97bb1217ac45f3e","name":"https://git.kernel.org/stable/c/5313d4d41739b0cb63000747c97bb1217ac45f3e","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/2cf9f50a38c1839e549a08e22aa35e8d69e2c8fd","name":"https://git.kernel.org/stable/c/2cf9f50a38c1839e549a08e22aa35e8d69e2c8fd","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/ac34e655dffa74349d885a43d098115336f53842","name":"https://git.kernel.org/stable/c/ac34e655dffa74349d885a43d098115336f53842","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/083b58373463a6e5ee60ecb135269348f68ad7df","name":"https://git.kernel.org/stable/c/083b58373463a6e5ee60ecb135269348f68ad7df","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/b5dae1cd0d8368b4338430ff93403df67f0b8bcc","name":"https://git.kernel.org/stable/c/b5dae1cd0d8368b4338430ff93403df67f0b8bcc","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-90326","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-90326","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 81c1188905f88b77743d1fdeeedfc8cb7b67787d b5dae1cd0d8368b4338430ff93403df67f0b8bcc git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected bfe46d2efe46c5c952f982e2ca94fe2ec5e58e2a 083b58373463a6e5ee60ecb135269348f68ad7df git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected f1c006f1c6850c14040f8337753a63119bba39b9 ac34e655dffa74349d885a43d098115336f53842 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected f1c006f1c6850c14040f8337753a63119bba39b9 2cf9f50a38c1839e549a08e22aa35e8d69e2c8fd git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected f1c006f1c6850c14040f8337753a63119bba39b9 5313d4d41739b0cb63000747c97bb1217ac45f3e git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6.1.16 6.1.17 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6.2.3 6.2.4 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6.3","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.3 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.1.17 6.1.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.2.4 6.2.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.18.52 6.18.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.2.6 7.2.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.3-rc1 * original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":{"cve_year":"2026","cve_id":"90326","cve":"CVE-2026-90326","epss":"0.002000000","percentile":"0.101440000","score_date":"2026-09-18","updated_at":"2026-09-19 00:06:16"},"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","product":"Linux","programFiles":["block/blk-cgroup.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"b5dae1cd0d8368b4338430ff93403df67f0b8bcc","status":"affected","version":"81c1188905f88b77743d1fdeeedfc8cb7b67787d","versionType":"git"},{"lessThan":"083b58373463a6e5ee60ecb135269348f68ad7df","status":"affected","version":"bfe46d2efe46c5c952f982e2ca94fe2ec5e58e2a","versionType":"git"},{"lessThan":"ac34e655dffa74349d885a43d098115336f53842","status":"affected","version":"f1c006f1c6850c14040f8337753a63119bba39b9","versionType":"git"},{"lessThan":"2cf9f50a38c1839e549a08e22aa35e8d69e2c8fd","status":"affected","version":"f1c006f1c6850c14040f8337753a63119bba39b9","versionType":"git"},{"lessThan":"5313d4d41739b0cb63000747c97bb1217ac45f3e","status":"affected","version":"f1c006f1c6850c14040f8337753a63119bba39b9","versionType":"git"},{"lessThan":"6.1.17","status":"affected","version":"6.1.16","versionType":"semver"},{"lessThan":"6.2.4","status":"affected","version":"6.2.3","versionType":"semver"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["block/blk-cgroup.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"6.3"},{"lessThan":"6.3","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"6.1.*","status":"unaffected","version":"6.1.17","versionType":"semver"},{"lessThanOrEqual":"6.2.*","status":"unaffected","version":"6.2.4","versionType":"semver"},{"lessThanOrEqual":"6.18.*","status":"unaffected","version":"6.18.52","versionType":"semver"},{"lessThanOrEqual":"7.2.*","status":"unaffected","version":"7.2.6","versionType":"semver"},{"lessThanOrEqual":"*","status":"unaffected","version":"7.3-rc1","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.1.17","versionStartIncluding":"6.1.16","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.2.4","versionStartIncluding":"6.2.3","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.18.52","versionStartIncluding":"6.3","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.2.6","versionStartIncluding":"6.3","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.3-rc1","versionStartIncluding":"6.3","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"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_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."}],"metrics":[{"cvssV3_1":{"baseScore":7.8,"baseSeverity":"HIGH","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","version":"3.1"},"scenarios":[{"lang":"en","value":"AV:L - The triggering operations are local cgroupfs writes: tg_set_limit() (io.max) or iolatency_set_limit() (io.latency) call blk_throtl_init()/blk_iolatency_init() then blkcg_activate_policy(), while cgroup_rmdir() runs blkcg_css_offline() into blkg_free_workfn(); elv_iosched_store() is an alternate local sysfs path. No remote protocol carries the race inputs.\nAC:L - The attacker drives both sides: one thread writes io.max/io.latency so blkcg_activate_policy() attaches pd without q->blkcg_mutex, while another rmdirs sibling blkcgs so blkg_free_workfn() calls pd_free_fn() on the same blkg->pd[] before list_del. That interleaving does not depend on GFP_KERNEL failure; the documented enomem rollback UAF on pd->online is an extra window the attacker can retry.\nPR:L - tg_set_limit() and iolatency_set_limit() have no capable() check; io.max/io.latency are CFTYPE_NOT_ON_ROOT S_IWUSR files, and blkg_conf_open_bdev() uses blkdev_get_no_open() with no device permission check. A delegated cgroup-v2 subtree owner (typical systemd user slice or rootless container) can write those files and rmdir child cgroups; scheduler sysfs is a stricter alternate path.\nUI:N - The attacker writes io.max/io.latency in cgroups they own and rmdirs those cgroups themselves; no other user must mount a device, open a file, or otherwise participate.\nS:U - The UAF corrupts kernel blkg_policy_data (throtl_grp/iolatency_grp) in the host io controller; impact stays in the kernel's authority and does not cross a VM, IOMMU, or other security boundary.\nC:H - blkg_free_workfn() frees blkg->pd[] while the object remains on q->blkg_list, so blkcg_activate_policy()'s enomem path reads pd->online and pd_offline_fn() (throtl_pd_offline()/tg_flush_bios()) walks the freed throtl_grp; spraying the slab reclaims that object for an arbitrary kernel read.\nI:H - The same freed pd is written (pd->online = false) and passed to pol->pd_free_fn() again (throtl_pd_free() does timer_delete_sync() and call_rcu()), a double-free of throtl_grp/iolatency_grp that yields a kernel write/control-flow primitive.\nA:H - Use-after-free and double-free of blkg_policy_data in blkcg_activate_policy() versus blkg_free_workfn() oops/panic the kernel even when not turned into a full memory primitive."}]}],"providerMetadata":{"dateUpdated":"2026-09-18T17:54:39.274Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/b5dae1cd0d8368b4338430ff93403df67f0b8bcc"},{"url":"https://git.kernel.org/stable/c/083b58373463a6e5ee60ecb135269348f68ad7df"},{"url":"https://git.kernel.org/stable/c/ac34e655dffa74349d885a43d098115336f53842"},{"url":"https://git.kernel.org/stable/c/2cf9f50a38c1839e549a08e22aa35e8d69e2c8fd"},{"url":"https://git.kernel.org/stable/c/5313d4d41739b0cb63000747c97bb1217ac45f3e"}],"title":"blk-cgroup: fix race between policy activation and blkg destruction","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-90326","datePublished":"2026-09-17T16:08:41.374Z","dateReserved":"2026-09-11T19:38:34.802Z","dateUpdated":"2026-09-18T17:54:39.274Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-09-17 17:17:30","lastModifiedDate":"2026-09-18 18:17:54","problem_types":[],"metrics":{"cvssMetricV31":[{"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","type":"Secondary","cvssData":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","baseScore":7.8,"baseSeverity":"HIGH","attackVector":"LOCAL","attackComplexity":"LOW","privilegesRequired":"LOW","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"HIGH"},"exploitabilityScore":1.8,"impactScore":5.9}]},"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"90326","Ordinal":"1","Title":"blk-cgroup: fix race between policy activation and blkg destruct","CVE":"CVE-2026-90326","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"90326","Ordinal":"1","NoteData":"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_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.","Type":"Description","Title":"blk-cgroup: fix race between policy activation and blkg destruct"}]}}}