CVE-2026-45839 (GCVE-0-2026-45839)
Vulnerability from cvelistv5
Published
2026-05-27 09:24
Modified
2026-06-14 17:46
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: bpf: reject negative CO-RE accessor indices in bpf_core_parse_spec() CO-RE accessor strings are colon-separated indices that describe a path from a root BTF type to a target field, e.g. "0:1:2" walks through nested struct members. bpf_core_parse_spec() parses each component with sscanf("%d"), so negative values like -1 are silently accepted. The subsequent bounds checks (access_idx >= btf_vlen(t)) only guard the upper bound and always pass for negative values because C integer promotion converts the __u16 btf_vlen result to int, making the comparison (int)(-1) >= (int)(N) false for any positive N. When -1 reaches btf_member_bit_offset() it gets cast to u32 0xffffffff, producing an out-of-bounds read far past the members array. A crafted BPF program with a negative CO-RE accessor on any struct that exists in vmlinux BTF (e.g. task_struct) crashes the kernel deterministically during BPF_PROG_LOAD on any system with CONFIG_DEBUG_INFO_BTF=y (default on major distributions). The bug is reachable with CAP_BPF: BUG: unable to handle page fault for address: ffffed11818b6626 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page Oops: Oops: 0000 [#1] SMP KASAN NOPTI CPU: 0 UID: 0 PID: 85 Comm: poc Not tainted 7.0.0-rc6 #18 PREEMPT(full) RIP: 0010:bpf_core_parse_spec (tools/lib/bpf/relo_core.c:354) RAX: 00000000ffffffff Call Trace: <TASK> bpf_core_calc_relo_insn (tools/lib/bpf/relo_core.c:1321) bpf_core_apply (kernel/bpf/btf.c:9507) check_core_relo (kernel/bpf/verifier.c:19475) bpf_check (kernel/bpf/verifier.c:26031) bpf_prog_load (kernel/bpf/syscall.c:3089) __sys_bpf (kernel/bpf/syscall.c:6228) </TASK> CO-RE accessor indices are inherently non-negative (struct member index, array element index, or enumerator index), so reject them immediately after parsing.
Impacted products
Vendor Product Version
Linux Linux Version: ddc7c3042614e273044f698d2beab25cc3842d45
Version: ddc7c3042614e273044f698d2beab25cc3842d45
Version: ddc7c3042614e273044f698d2beab25cc3842d45
Version: ddc7c3042614e273044f698d2beab25cc3842d45
Version: ddc7c3042614e273044f698d2beab25cc3842d45
Version: ddc7c3042614e273044f698d2beab25cc3842d45
Version: ddc7c3042614e273044f698d2beab25cc3842d45
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{
  "containers": {
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          "programFiles": [
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          "product": "Linux",
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          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
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            },
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              "version": "0",
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              "version": "5.15.209",
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              "version": "6.1.175",
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              "version": "6.6.141",
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              "version": "6.12.91",
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              "lessThanOrEqual": "6.18.*",
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              "version": "7.0.10",
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            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.1",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
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                  "vulnerable": true
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              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: reject negative CO-RE accessor indices in bpf_core_parse_spec()\n\nCO-RE accessor strings are colon-separated indices that describe a path\nfrom a root BTF type to a target field, e.g. \"0:1:2\" walks through\nnested struct members. bpf_core_parse_spec() parses each component with\nsscanf(\"%d\"), so negative values like -1 are silently accepted.  The\nsubsequent bounds checks (access_idx \u003e= btf_vlen(t)) only guard the\nupper bound and always pass for negative values because C integer\npromotion converts the __u16 btf_vlen result to int, making the\ncomparison (int)(-1) \u003e= (int)(N) false for any positive N.\n\nWhen -1 reaches btf_member_bit_offset() it gets cast to u32 0xffffffff,\nproducing an out-of-bounds read far past the members array.  A crafted\nBPF program with a negative CO-RE accessor on any struct that exists in\nvmlinux BTF (e.g. task_struct) crashes the kernel deterministically\nduring BPF_PROG_LOAD on any system with CONFIG_DEBUG_INFO_BTF=y\n(default on major distributions).  The bug is reachable with CAP_BPF:\n\n BUG: unable to handle page fault for address: ffffed11818b6626\n #PF: supervisor read access in kernel mode\n #PF: error_code(0x0000) - not-present page\n Oops: Oops: 0000 [#1] SMP KASAN NOPTI\n CPU: 0 UID: 0 PID: 85 Comm: poc Not tainted 7.0.0-rc6 #18 PREEMPT(full)\n RIP: 0010:bpf_core_parse_spec (tools/lib/bpf/relo_core.c:354)\n RAX: 00000000ffffffff\n Call Trace:\n  \u003cTASK\u003e\n  bpf_core_calc_relo_insn (tools/lib/bpf/relo_core.c:1321)\n  bpf_core_apply (kernel/bpf/btf.c:9507)\n  check_core_relo (kernel/bpf/verifier.c:19475)\n  bpf_check (kernel/bpf/verifier.c:26031)\n  bpf_prog_load (kernel/bpf/syscall.c:3089)\n  __sys_bpf (kernel/bpf/syscall.c:6228)\n  \u003c/TASK\u003e\n\nCO-RE accessor indices are inherently non-negative (struct member index,\narray element index, or enumerator index), so reject them immediately\nafter parsing."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-06-14T17:46:08.677Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/a9e777f856cd2f1efc106afc7bf21aef868509d5"
        },
        {
          "url": "https://git.kernel.org/stable/c/669349b4612c26b3d7aacfa99d7174681bd19223"
        },
        {
          "url": "https://git.kernel.org/stable/c/3ff85ae79e1a74baeb916b78a63d821f6d19a994"
        },
        {
          "url": "https://git.kernel.org/stable/c/36a9012f76ba8d9189ae56a1f8bb7c87c07a1f3a"
        },
        {
          "url": "https://git.kernel.org/stable/c/76f2ebaf79a9ae6d0737b87f045fe769e425d78f"
        },
        {
          "url": "https://git.kernel.org/stable/c/99dbab7b5a12d8f58d5b0aa2f7a1fe656a70f4b2"
        },
        {
          "url": "https://git.kernel.org/stable/c/1c22483a2c4bbf747787f328392ca3e68619c4dc"
        }
      ],
      "title": "bpf: reject negative CO-RE accessor indices in bpf_core_parse_spec()",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-45839",
    "datePublished": "2026-05-27T09:24:37.855Z",
    "dateReserved": "2026-05-13T15:03:33.077Z",
    "dateUpdated": "2026-06-14T17:46:08.677Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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