{"api_version":"1","generated_at":"2026-10-24T19:34:58+00:00","cve":"CVE-2026-99065","urls":{"html":"https://cve.report/CVE-2026-99065","api":"https://cve.report/api/cve/CVE-2026-99065.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-99065","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-99065"},"summary":{"title":"cgroup/cpuset: Handle cpu hotplug race in guarantee_active_cpus()","description":"In the Linux kernel, the following vulnerability has been resolved:\n\ncgroup/cpuset: Handle cpu hotplug race in guarantee_active_cpus()\n\nWith commit 2125c0034c5d (\"cgroup/cpuset: Make cpuset hotplug processing\nsynchronous\"), the cpuset hotplug operation becomes synchronous. That\ncommit also removes the code that handles race between cpuset_hotplug_work\nand cpu hotplug notifier with the assumption that race is now gone.\nLater commit 7a0aabd9ce69 (\"cgroup/cpuset: Always use cpu_active_mask\")\nupdates the cpuset code to always use cpu_active_mask instead of\ncpu_online_mask in some places including guarantee_online_cpus() which\nis renamed to guarantee_active_cpus() in that commit.\n\nIn the case of CPU offline operation, cpu_active_mask is updated\nfirst in sched_cpu_deactivate() to remove the offline CPU before\ncpuset_handle_hotplug() is called to update the effective_cpus of the\naffected cpusets. The cpu_online_mask is updated after that near the end\nof the offline operation to remove the offline CPU. As a result, the race\ncomes back and the top cpuset may not have any active CPU leading to NULL\npointer dereference during the race window when guarantee_active_cpus()\nis called after cpu_active_mask is updated to remove the CPU to be torn\ndown but before cpuset_handle_hotplug() is able to properly update the\neffective_cpus of the top cpuset.\n\nFix this by adding back the NULL cs check to avoid this problem.","state":"PUBLISHED","assigner":"Linux","published_at":"2026-10-23 13:17:30","updated_at":"2026-10-23 13:17:30"},"problem_types":[],"metrics":[],"references":[{"url":"https://git.kernel.org/stable/c/8d88d3221204fbb1b6dc2c0f2f2181fe49126639","name":"https://git.kernel.org/stable/c/8d88d3221204fbb1b6dc2c0f2f2181fe49126639","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/a21c255159bfe0034740292e10d2e258feeeb10d","name":"https://git.kernel.org/stable/c/a21c255159bfe0034740292e10d2e258feeeb10d","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/23b1ab15ca91f2cffaf149d9bb0fafeb700c7db2","name":"https://git.kernel.org/stable/c/23b1ab15ca91f2cffaf149d9bb0fafeb700c7db2","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-99065","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-99065","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 7a0aabd9ce697fc581ec691b21f748050fbcf004 8d88d3221204fbb1b6dc2c0f2f2181fe49126639 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 7a0aabd9ce697fc581ec691b21f748050fbcf004 a21c255159bfe0034740292e10d2e258feeeb10d git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 7a0aabd9ce697fc581ec691b21f748050fbcf004 23b1ab15ca91f2cffaf149d9bb0fafeb700c7db2 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6.16","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.16 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.18.57 6.18.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.2.11 7.2.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.3 * original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":null,"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","product":"Linux","programFiles":["kernel/cgroup/cpuset.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"8d88d3221204fbb1b6dc2c0f2f2181fe49126639","status":"affected","version":"7a0aabd9ce697fc581ec691b21f748050fbcf004","versionType":"git"},{"lessThan":"a21c255159bfe0034740292e10d2e258feeeb10d","status":"affected","version":"7a0aabd9ce697fc581ec691b21f748050fbcf004","versionType":"git"},{"lessThan":"23b1ab15ca91f2cffaf149d9bb0fafeb700c7db2","status":"affected","version":"7a0aabd9ce697fc581ec691b21f748050fbcf004","versionType":"git"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["kernel/cgroup/cpuset.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"6.16"},{"lessThan":"6.16","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"6.18.*","status":"unaffected","version":"6.18.57","versionType":"semver"},{"lessThanOrEqual":"7.2.*","status":"unaffected","version":"7.2.11","versionType":"semver"},{"lessThanOrEqual":"*","status":"unaffected","version":"7.3","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.18.57","versionStartIncluding":"6.16","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.2.11","versionStartIncluding":"6.16","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.3","versionStartIncluding":"6.16","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\ncgroup/cpuset: Handle cpu hotplug race in guarantee_active_cpus()\n\nWith commit 2125c0034c5d (\"cgroup/cpuset: Make cpuset hotplug processing\nsynchronous\"), the cpuset hotplug operation becomes synchronous. That\ncommit also removes the code that handles race between cpuset_hotplug_work\nand cpu hotplug notifier with the assumption that race is now gone.\nLater commit 7a0aabd9ce69 (\"cgroup/cpuset: Always use cpu_active_mask\")\nupdates the cpuset code to always use cpu_active_mask instead of\ncpu_online_mask in some places including guarantee_online_cpus() which\nis renamed to guarantee_active_cpus() in that commit.\n\nIn the case of CPU offline operation, cpu_active_mask is updated\nfirst in sched_cpu_deactivate() to remove the offline CPU before\ncpuset_handle_hotplug() is called to update the effective_cpus of the\naffected cpusets. The cpu_online_mask is updated after that near the end\nof the offline operation to remove the offline CPU. As a result, the race\ncomes back and the top cpuset may not have any active CPU leading to NULL\npointer dereference during the race window when guarantee_active_cpus()\nis called after cpu_active_mask is updated to remove the CPU to be torn\ndown but before cpuset_handle_hotplug() is able to properly update the\neffective_cpus of the top cpuset.\n\nFix this by adding back the NULL cs check to avoid this problem."}],"providerMetadata":{"dateUpdated":"2026-10-23T12:23:08.458Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/8d88d3221204fbb1b6dc2c0f2f2181fe49126639"},{"url":"https://git.kernel.org/stable/c/a21c255159bfe0034740292e10d2e258feeeb10d"},{"url":"https://git.kernel.org/stable/c/23b1ab15ca91f2cffaf149d9bb0fafeb700c7db2"}],"title":"cgroup/cpuset: Handle cpu hotplug race in guarantee_active_cpus()","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-99065","datePublished":"2026-10-23T12:23:08.458Z","dateReserved":"2026-09-25T10:25:14.389Z","dateUpdated":"2026-10-23T12:23:08.458Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-10-23 13:17:30","lastModifiedDate":"2026-10-23 13:17:30","problem_types":[],"metrics":[],"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"99065","Ordinal":"1","Title":"cgroup/cpuset: Handle cpu hotplug race in guarantee_active_cpus(","CVE":"CVE-2026-99065","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"99065","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\ncgroup/cpuset: Handle cpu hotplug race in guarantee_active_cpus()\n\nWith commit 2125c0034c5d (\"cgroup/cpuset: Make cpuset hotplug processing\nsynchronous\"), the cpuset hotplug operation becomes synchronous. That\ncommit also removes the code that handles race between cpuset_hotplug_work\nand cpu hotplug notifier with the assumption that race is now gone.\nLater commit 7a0aabd9ce69 (\"cgroup/cpuset: Always use cpu_active_mask\")\nupdates the cpuset code to always use cpu_active_mask instead of\ncpu_online_mask in some places including guarantee_online_cpus() which\nis renamed to guarantee_active_cpus() in that commit.\n\nIn the case of CPU offline operation, cpu_active_mask is updated\nfirst in sched_cpu_deactivate() to remove the offline CPU before\ncpuset_handle_hotplug() is called to update the effective_cpus of the\naffected cpusets. The cpu_online_mask is updated after that near the end\nof the offline operation to remove the offline CPU. As a result, the race\ncomes back and the top cpuset may not have any active CPU leading to NULL\npointer dereference during the race window when guarantee_active_cpus()\nis called after cpu_active_mask is updated to remove the CPU to be torn\ndown but before cpuset_handle_hotplug() is able to properly update the\neffective_cpus of the top cpuset.\n\nFix this by adding back the NULL cs check to avoid this problem.","Type":"Description","Title":"cgroup/cpuset: Handle cpu hotplug race in guarantee_active_cpus("}]}}}