{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-74731", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-08-15T05:44:03.930Z", "datePublished": "2026-08-22T15:33:20.294Z", "dateUpdated": "2026-08-25T05:42:10.750Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-25T05:42:10.750Z"}, "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nsched_ext: Skip sub-disable teardown for never-linked sub-schedulers\n\nA sub-scheduler enable can fail before scx_link_sched() links the sched into\nthe hierarchy, e.g. when the parent is already being disabled, and cleanup\nstill runs the full scx_sub_disable().\n\nThat is racy against root disable: drain_descendants() is the only ordering\nbetween a sub's disable-time task walk and root disable's all-task teardown,\nand an unlinked sub is invisible to it. Root's teardown can thus run between\nthe never-linked sub's drain and its walk, exiting every task to no\nscheduler.\n\nThe walk then trips the membership WARN and re-homes the exited tasks onto\nthe dying hierarchy, a use-after-free.\n\nSkip the cgroup ownership reset and the task walk if @sch was never linked,\nindicated by the empty ->sibling as unlinking only happens later in the same\nfunction. The membership WARN remains valid: a linked sub is always waited\non by an ancestor's drain."}], "metrics": [{"cvssV3_1": {"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"}, "scenarios": [{"lang": "en", "value": "AV:L - The bug is reached only via local bpf(2) syscalls (BPF_MAP_CREATE/UPDATE_ELEM, BPF_PROG_LOAD, BPF_LINK_CREATE) that register sched_ext_ops struct_ops and invoke scx_enable()/scx_sub_enable_workfn(); per kernel CNA guidance BPF/sched_ext is Local, not network-reachable.\nAC:L - The attacker controls both sides of the race by concurrently attaching a sub-scheduler and closing the root BPF link to trigger scx_root_disable() while never-linked sub cleanup runs scx_sub_disable(); repeated attempts can reliably hit the window between drain_descendants() and the task walk.\nPR:L - Exploitation requires CAP_BPF to create BPF_MAP_TYPE_STRUCT_OPS, load BPF_PROG_TYPE_STRUCT_OPS, and BPF_LINK_CREATE sched_ext; per kernel guidance this is Low because CAP_BPF is obtainable via user namespaces/BPF tokens, not init-namespace root only.\nUI:N - No victim interaction is required; the attacker loads root and sub BPF schedulers, targets their cgroup, and closes BPF links from their own processes to orchestrate the concurrent enable-failure and teardown race.\nS:U - The use-after-free corrupts kernel scheduler/task state during sched_ext teardown on the same host kernel; this is standard kernel memory corruption and privilege escalation impact, not a VM escape or cross-security-authority boundary.\nC:H - Failed never-linked sub cleanup re-homes tasks onto a dying scx_sched hierarchy after root disable frees scheduler state; this use-after-free on scheduler/task metadata can be leveraged for arbitrary kernel memory disclosure per kernel UAF guidance.\nI:H - The UAF during scx_set_task_sched()/scx_enable_task() on a freed scx_sched corrupts scheduler pointers and task ownership in the system-wide scheduler path, enabling heap corruption and arbitrary kernel write or code execution primitives.\nA:H - The race re-homes tasks onto a tearing-down sched_ext hierarchy, tripping membership WARNs and corrupting scheduler teardown; this causes kernel oops/panic/hang on a system-wide scheduler subsystem, which is High availability impact per kernel guidance."}]}], "affected": [{"product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["kernel/sched/ext/ext.c"], "versions": [{"version": "337ec00b1d9c676f637651c2cefddb8612b867ee", "lessThan": "6428093a4a986c38c9089b5eb32b56d914ef437a", "status": "affected", "versionType": "git"}, {"version": "337ec00b1d9c676f637651c2cefddb8612b867ee", "lessThan": "8c13364db9c9a43ed286f3a8d0fb9477b1adc43c", "status": "affected", "versionType": "git"}]}, {"product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["kernel/sched/ext/ext.c"], "versions": [{"version": "7.1", "status": "affected"}, {"version": "0", "lessThan": "7.1", "status": "unaffected", "versionType": "semver"}, {"version": "7.1.9", "lessThanOrEqual": "7.1.*", "status": "unaffected", "versionType": "semver"}, {"version": "7.2", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix"}]}], "cpeApplicability": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "7.1", "versionEndExcluding": "7.1.9"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "7.1", "versionEndExcluding": "7.2"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/6428093a4a986c38c9089b5eb32b56d914ef437a"}, {"url": "https://git.kernel.org/stable/c/8c13364db9c9a43ed286f3a8d0fb9477b1adc43c"}], "title": "sched_ext: Skip sub-disable teardown for never-linked sub-schedulers", "x_generator": {"engine": "bippy-1.2.0"}}}}

{}

{"affected": [{"affectedData": [{"defaultStatus": "unaffected", "product": "Linux", "programFiles": ["kernel/sched/ext/ext.c"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"lessThan": "6428093a4a986c38c9089b5eb32b56d914ef437a", "status": "affected", "version": "337ec00b1d9c676f637651c2cefddb8612b867ee", "versionType": "git"}, {"lessThan": "8c13364db9c9a43ed286f3a8d0fb9477b1adc43c", "status": "affected", "version": "337ec00b1d9c676f637651c2cefddb8612b867ee", "versionType": "git"}]}, {"defaultStatus": "affected", "product": "Linux", "programFiles": ["kernel/sched/ext/ext.c"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"status": "affected", "version": "7.1"}, {"lessThan": "7.1", "status": "unaffected", "version": "0", "versionType": "semver"}, {"lessThanOrEqual": "7.1.*", "status": "unaffected", "version": "7.1.9", "versionType": "semver"}, {"lessThanOrEqual": "*", "status": "unaffected", "version": "7.2", "versionType": "original_commit_for_fix"}]}], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}], "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nsched_ext: Skip sub-disable teardown for never-linked sub-schedulers\n\nA sub-scheduler enable can fail before scx_link_sched() links the sched into\nthe hierarchy, e.g. when the parent is already being disabled, and cleanup\nstill runs the full scx_sub_disable().\n\nThat is racy against root disable: drain_descendants() is the only ordering\nbetween a sub's disable-time task walk and root disable's all-task teardown,\nand an unlinked sub is invisible to it. Root's teardown can thus run between\nthe never-linked sub's drain and its walk, exiting every task to no\nscheduler.\n\nThe walk then trips the membership WARN and re-homes the exited tasks onto\nthe dying hierarchy, a use-after-free.\n\nSkip the cgroup ownership reset and the task walk if @sch was never linked,\nindicated by the empty ->sibling as unlinking only happens later in the same\nfunction. The membership WARN remains valid: a linked sub is always waited\non by an ancestor's drain."}], "id": "CVE-2026-74731", "lastModified": "2026-08-25T06:18:59.753", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "LOCAL", "availabilityImpact": "HIGH", "baseScore": 7.8, "baseSeverity": "HIGH", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "LOW", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "version": "3.1"}, "exploitabilityScore": 1.8, "impactScore": 5.9, "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "type": "Secondary"}]}, "published": "2026-08-22T16:16:48.257", "references": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/6428093a4a986c38c9089b5eb32b56d914ef437a"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/8c13364db9c9a43ed286f3a8d0fb9477b1adc43c"}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "vulnStatus": "Received"}

{"bugzilla": {"description": "kernel: sched_ext: Skip sub-disable teardown for never-linked sub-schedulers", "id": "2521441", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2521441"}, "csaw": false, "cvss3": {"cvss3_base_score": "5.5", "cvss3_scoring_vector": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H", "status": "draft"}, "cwe": "CWE-364", "details": ["In the Linux kernel, the following vulnerability has been resolved:\nsched_ext: Skip sub-disable teardown for never-linked sub-schedulers\nA sub-scheduler enable can fail before scx_link_sched() links the sched into\nthe hierarchy, e.g. when the parent is already being disabled, and cleanup\nstill runs the full scx_sub_disable().\nThat is racy against root disable: drain_descendants() is the only ordering\nbetween a sub's disable-time task walk and root disable's all-task teardown,\nand an unlinked sub is invisible to it. Root's teardown can thus run between\nthe never-linked sub's drain and its walk, exiting every task to no\nscheduler.\nThe walk then trips the membership WARN and re-homes the exited tasks onto\nthe dying hierarchy, a use-after-free.\nSkip the cgroup ownership reset and the task walk if @sch was never linked,\nindicated by the empty ->sibling as unlinking only happens later in the same\nfunction. The membership WARN remains valid: a linked sub is always waited\non by an ancestor's drain.", "A flaw was found in the Linux kernel's `sched_ext` component. A race condition can occur during the disabling of a sub-scheduler that was never properly linked into the scheduler hierarchy. This can lead to a use-after-free vulnerability, where exited tasks are re-homed onto a dying hierarchy. This issue could potentially result in system instability or denial of service."], "name": "CVE-2026-74731", "package_state": [{"cpe": "cpe:/o:redhat:enterprise_linux:10", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 10"}, {"cpe": "cpe:/o:redhat:enterprise_linux:6", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 6"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Not affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Not affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 9"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Not affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 9"}], "public_date": "2026-08-22T00:00:00Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-74731\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-74731\nhttps://lore.kernel.org/linux-cve-announce/2026082242-CVE-2026-74731-9884@gregkh/T"], "threat_severity": "Moderate"}