{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-64036","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","state":"PUBLISHED","assignerShortName":"Linux","dateReserved":"2026-07-19T07:54:57.028Z","datePublished":"2026-07-19T15:39:24.783Z","dateUpdated":"2026-08-05T12:38:30.669Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2026-08-05T12:38:30.669Z"},"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\ncgroup/rstat: validate cpu before css_rstat_cpu() access\n\ncss_rstat_updated() is exposed as a BPF kfunc and accepts a\ncaller-provided cpu argument. The function uses cpu for per-cpu rstat\nlookups without checking whether it refers to a valid possible CPU.\n\nA BPF iter/cgroup program with CAP_BPF and CAP_PERFMON can pass an\ninvalid cpu value. On an unfixed UBSCAN_BOUNDS test kernel, cpu ==\n0x7fffffff triggers:\n\n  UBSAN: array-index-out-of-bounds in kernel/cgroup/rstat.c:31:9\n  index 2147483647 is out of range for type 'long unsigned int [64]'\n  Call Trace:\n    css_rstat_updated\n    bpf_iter_run_prog\n    cgroup_iter_seq_show\n    bpf_seq_read\n\nAdd cpu validation to the BPF-facing css_rstat_updated() kfunc and\nmove the common implementation to __css_rstat_updated() for in-kernel\ncallers."}],"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 - Exploitation requires loading and running a BPF cgroup iterator/tracing program via local syscalls (bpf, read on iter fd); the call chain is css_rstat_updated → bpf_iter_run_prog → cgroup_iter_seq_show → bpf_seq_read, with no network-facing entry point.\nAC:L - The attacker fully controls the cpu argument passed from BPF (e.g. 0x7fffffff) and can trigger the bug deterministically on each iter read without races or victim-specific state.\nPR:L - Exploitation requires CAP_BPF and CAP_PERFMON to load and run BPF_PROG_TYPE_TRACING/cgroup-iter programs that can invoke the css_rstat_updated kfunc, as stated in the fix commit; these are elevated but not full init-namespace root privileges.\nUI:N - No victim interaction is required; the attacker triggers the bug by loading their own BPF program and reading from the attached iterator file descriptor.\nS:U - The vulnerability corrupts kernel memory from within kernel BPF context on the same host; it does not cross a VM/hypervisor or IOMMU security boundary.\nC:H - An invalid cpu indexes __per_cpu_offset[] out of bounds and yields a wild pointer used for structure reads (llist_on_list), enabling kernel memory disclosure beyond a bounded leak.\nI:H - The same out-of-bounds pointer is written via try_cmpxchg on llist_node.next and llist_add into a per-CPU list head, giving exploitable out-of-bounds kernel memory corruption.\nA:H - Operating on attacker-chosen out-of-bounds kernel addresses can cause kernel oops, panic, or hang during the corrupting cmpxchg/list operations."}]}],"affected":[{"product":"Linux","vendor":"Linux","defaultStatus":"unaffected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["block/blk-cgroup.c","include/linux/cgroup.h","kernel/cgroup/rstat.c","mm/memcontrol.c"],"versions":[{"version":"a319185be9f5ad13c2a296d448ac52ffe45d194c","lessThan":"6a01413a4e8fcb0263d7bef5075c5f8f4eb3a8b6","status":"affected","versionType":"git"},{"version":"a319185be9f5ad13c2a296d448ac52ffe45d194c","lessThan":"fd2bd9fa7700ddf28296486b2598cff2f80cc819","status":"affected","versionType":"git"},{"version":"a319185be9f5ad13c2a296d448ac52ffe45d194c","lessThan":"8817005efbdfdf5d4e4814cb5dc52b53d12917d7","status":"affected","versionType":"git"}]},{"product":"Linux","vendor":"Linux","defaultStatus":"affected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["block/blk-cgroup.c","include/linux/cgroup.h","kernel/cgroup/rstat.c","mm/memcontrol.c"],"versions":[{"version":"6.1","status":"affected"},{"version":"0","lessThan":"6.1","status":"unaffected","versionType":"semver"},{"version":"6.18.34","lessThanOrEqual":"6.18.*","status":"unaffected","versionType":"semver"},{"version":"7.0.11","lessThanOrEqual":"7.0.*","status":"unaffected","versionType":"semver"},{"version":"7.1","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":"6.1","versionEndExcluding":"6.18.34"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.1","versionEndExcluding":"7.0.11"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.1","versionEndExcluding":"7.1"}]}]}],"references":[{"url":"https://git.kernel.org/stable/c/6a01413a4e8fcb0263d7bef5075c5f8f4eb3a8b6"},{"url":"https://git.kernel.org/stable/c/fd2bd9fa7700ddf28296486b2598cff2f80cc819"},{"url":"https://git.kernel.org/stable/c/8817005efbdfdf5d4e4814cb5dc52b53d12917d7"}],"title":"cgroup/rstat: validate cpu before css_rstat_cpu() access","x_generator":{"engine":"bippy-1.2.0"}}}}