{ "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" } } } }