CVE-2026-64036 (GCVE-0-2026-64036)
Vulnerability from cvelistv5
Published
2026-07-19 15:39
Modified
2026-08-05 12:38
Severity ?
7.8 (High) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: cgroup/rstat: validate cpu before css_rstat_cpu() access css_rstat_updated() is exposed as a BPF kfunc and accepts a caller-provided cpu argument. The function uses cpu for per-cpu rstat lookups without checking whether it refers to a valid possible CPU. A BPF iter/cgroup program with CAP_BPF and CAP_PERFMON can pass an invalid cpu value. On an unfixed UBSCAN_BOUNDS test kernel, cpu == 0x7fffffff triggers: UBSAN: array-index-out-of-bounds in kernel/cgroup/rstat.c:31:9 index 2147483647 is out of range for type 'long unsigned int [64]' Call Trace: css_rstat_updated bpf_iter_run_prog cgroup_iter_seq_show bpf_seq_read Add cpu validation to the BPF-facing css_rstat_updated() kfunc and move the common implementation to __css_rstat_updated() for in-kernel callers.
References
Impacted products
Vendor Product Version
Linux Linux Version: a319185be9f5ad13c2a296d448ac52ffe45d194c
Version: a319185be9f5ad13c2a296d448ac52ffe45d194c
Version: a319185be9f5ad13c2a296d448ac52ffe45d194c
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "block/blk-cgroup.c",
            "include/linux/cgroup.h",
            "kernel/cgroup/rstat.c",
            "mm/memcontrol.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "6a01413a4e8fcb0263d7bef5075c5f8f4eb3a8b6",
              "status": "affected",
              "version": "a319185be9f5ad13c2a296d448ac52ffe45d194c",
              "versionType": "git"
            },
            {
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              "status": "affected",
              "version": "a319185be9f5ad13c2a296d448ac52ffe45d194c",
              "versionType": "git"
            },
            {
              "lessThan": "8817005efbdfdf5d4e4814cb5dc52b53d12917d7",
              "status": "affected",
              "version": "a319185be9f5ad13c2a296d448ac52ffe45d194c",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "block/blk-cgroup.c",
            "include/linux/cgroup.h",
            "kernel/cgroup/rstat.c",
            "mm/memcontrol.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.1"
            },
            {
              "lessThan": "6.1",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.34",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.0.*",
              "status": "unaffected",
              "version": "7.0.11",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.1",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.34",
                  "versionStartIncluding": "6.1",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.0.11",
                  "versionStartIncluding": "6.1",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.1",
                  "versionStartIncluding": "6.1",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "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 \u0027long unsigned int [64]\u0027\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": {
            "baseScore": 7.8,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "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 \u2192 bpf_iter_run_prog \u2192 cgroup_iter_seq_show \u2192 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."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-05T12:38:30.669Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "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"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-64036",
    "datePublished": "2026-07-19T15:39:24.783Z",
    "dateReserved": "2026-07-19T07:54:57.028Z",
    "dateUpdated": "2026-08-05T12:38:30.669Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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