bpf: Reset register ID for BPF_END value tracking

{
  "id": "b82c318e953da1ead278b0fc9108bc66ecd93a4f43622ad90e36facb24ea647c",
  "url": "https://osv.dev/vulnerability/CVE-2026-43070",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "bpf: Reset register ID for BPF_END value tracking",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: bpf: Reset register ID for BPF_END value tracking When a register undergoes a BPF_END (byte swap) operation, its scalar value is mutated in-place. If this register previously shared a scalar ID with another register (e.g., after an `r1 = r0` assignment), this tie must be broken. Currently, the verifier misses resetting `dst_reg->id` to 0 for BPF_END. Consequently, if a conditional jump checks the swapped register, the verifier incorrectly propagates the learned bounds to the linked register, leading to false confidence in the linked register's value and potentially allowing out-of-bounds memory accesses. Fix this by explicitly resetting `dst_reg->id` to 0 in the BPF_END case to break the scalar tie, similar to how BPF_NEG handles it via `__mark_reg_known`.",
    "evidence": "osv:CVE-2026-43070",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "6.18.21",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.19.11",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "high",
    "structured": {
      "id": "CVE-2026-43070",
      "aliases": [
        "CVE-2026-43070"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"
        }
      ],
      "affected": [
        {
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              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
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          "versions": [
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            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-43070.json"
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        {
          "ranges": [
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              "type": "ECOSYSTEM",
              "events": [
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                  "introduced": "6.18.17"
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                  "fixed": "6.18.21"
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            {
              "type": "ECOSYSTEM",
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          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-43070.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:36.040922531Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/0d15c3611a2cc5d08993545d4032055ae10ae2c1",
        "https://git.kernel.org/stable/c/a17443af874229408ce6b78e2c8a2b5adeb4b7d8",
        "https://git.kernel.org/stable/c/a3125bc01884431d30d731461634c8295b6f0529",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/43xxx/CVE-2026-43070.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-43070",
        "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
      ],
      "provider_metadata": {
        "cna_assigner": "Linux",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/43xxx/CVE-2026-43070.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-43070",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 503109,
  "published_at": "2026-05-05T15:23:28.819+00:00"
}