{"schema":"threatline.record/2","record":{"id":"CVE-2026-99065","aliases":[],"summary":"cgroup/cpuset: Handle cpu hotplug race in guarantee_active_cpus()","details":"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.","categories":["Operating systems"],"product":"Linux","vendor":"Linux","ecosystem":null,"affected_ranges":[{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-99065","source_modified_at":"2026-10-23T12:23:08.458Z","fetched_at":"2026-10-23T18:42:43.628194Z","product":"Linux","vendor":"Linux","versions":[{"version":"7a0aabd9ce697fc581ec691b21f748050fbcf004","lessThan":"8d88d3221204fbb1b6dc2c0f2f2181fe49126639","status":"affected","versionType":"git"},{"version":"7a0aabd9ce697fc581ec691b21f748050fbcf004","lessThan":"a21c255159bfe0034740292e10d2e258feeeb10d","status":"affected","versionType":"git"},{"version":"7a0aabd9ce697fc581ec691b21f748050fbcf004","lessThan":"23b1ab15ca91f2cffaf149d9bb0fafeb700c7db2","status":"affected","versionType":"git"}],"defaultStatus":"unaffected"},{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-99065","source_modified_at":"2026-10-23T12:23:08.458Z","fetched_at":"2026-10-23T18:42:43.628194Z","product":"Linux","vendor":"Linux","versions":[{"version":"6.16","status":"affected"},{"version":"0","lessThan":"6.16","status":"unaffected","versionType":"semver"},{"version":"6.18.57","lessThanOrEqual":"6.18.*","status":"unaffected","versionType":"semver"},{"version":"7.2.11","lessThanOrEqual":"7.2.*","status":"unaffected","versionType":"semver"},{"version":"7.3","lessThanOrEqual":"*","status":"unaffected","versionType":"original_commit_for_fix"}],"defaultStatus":"affected"}],"fixed_versions":[{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-99065","source_modified_at":"2026-10-23T12:23:08.458Z","fetched_at":"2026-10-23T18:42:43.628194Z","package":{"name":"Linux","ecosystem":null},"version":"8d88d3221204fbb1b6dc2c0f2f2181fe49126639","basis":"first unaffected version stated in the CVE record"},{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-99065","source_modified_at":"2026-10-23T12:23:08.458Z","fetched_at":"2026-10-23T18:42:43.628194Z","package":{"name":"Linux","ecosystem":null},"version":"23b1ab15ca91f2cffaf149d9bb0fafeb700c7db2","basis":"first unaffected version stated in the CVE record"}],"cvss":null,"severity":null,"kev":{"listed":false},"epss":{"probability":null,"percentile":null,"score_date":null},"published_at":"2026-10-23T12:23:08.458Z","modified_at":"2026-10-23T12:23:08.458Z","provenance":[{"source":"CVE List","url":"https://www.cve.org/CVERecord?id=CVE-2026-99065","fetched_at":"2026-10-23T18:42:43.628194Z","source_modified_at":"2026-10-23T12:23:08.458Z"}],"sources":["CVE List"],"references":[{"source":"CVE List","url":"https://git.kernel.org/stable/c/8d88d3221204fbb1b6dc2c0f2f2181fe49126639"},{"source":"CVE List","url":"https://git.kernel.org/stable/c/a21c255159bfe0034740292e10d2e258feeeb10d"},{"source":"CVE List","url":"https://git.kernel.org/stable/c/23b1ab15ca91f2cffaf149d9bb0fafeb700c7db2"}],"locations":[],"motoko_assessment":{"status":"requires_architecture_review","automatic_remediation":false},"cve_state":"PUBLISHED","classification":{"method":"product-first software-layer rules","rules_version":"2.1","matched_on":"product","confidence":"heuristic","reviewed":false},"change_timestamp":"2026-10-23T12:23:08.458Z","content_hash":"df912bfa6f394804331d1dcde8ee1ee9f528d633064a2aa588dbd2a4bd6f703a"}}