FKIE_CVE-2026-43070

Vulnerability from fkie_nvd - Published: 2026-05-05 16:16 - Updated: 2026-05-08 13:16
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: 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`.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/0d15c3611a2cc5d08993545d4032055ae10ae2c1
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/a17443af874229408ce6b78e2c8a2b5adeb4b7d8
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/a3125bc01884431d30d731461634c8295b6f0529
Impacted products
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{
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Reset register ID for BPF_END value tracking\n\nWhen a register undergoes a BPF_END (byte swap) operation, its scalar\nvalue is mutated in-place. If this register previously shared a scalar ID\nwith another register (e.g., after an `r1 = r0` assignment), this tie must\nbe broken.\n\nCurrently, the verifier misses resetting `dst_reg-\u003eid` to 0 for BPF_END.\nConsequently, if a conditional jump checks the swapped register, the\nverifier incorrectly propagates the learned bounds to the linked register,\nleading to false confidence in the linked register\u0027s value and potentially\nallowing out-of-bounds memory accesses.\n\nFix this by explicitly resetting `dst_reg-\u003eid` to 0 in the BPF_END case\nto break the scalar tie, similar to how BPF_NEG handles it via\n`__mark_reg_known`."
    }
  ],
  "id": "CVE-2026-43070",
  "lastModified": "2026-05-08T13:16:37.750",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "LOCAL",
          "availabilityImpact": "HIGH",
          "baseScore": 7.8,
          "baseSeverity": "HIGH",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "privilegesRequired": "LOW",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 1.8,
        "impactScore": 5.9,
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "type": "Secondary"
      }
    ]
  },
  "published": "2026-05-05T16:16:16.320",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/0d15c3611a2cc5d08993545d4032055ae10ae2c1"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/a17443af874229408ce6b78e2c8a2b5adeb4b7d8"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/a3125bc01884431d30d731461634c8295b6f0529"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Awaiting Analysis"
}


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