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CVE-2026-72111

Estado: RecibidaAlta (8.8)—

In the Linux kernel, the following vulnerability has been resolved:

bpf: Reset register bounds before narrowing retval range in check_mem_access()

When the BPF verifier processes a context load of an LSM hook return value, it calls __mark_reg_s32_range() to narrow the register to the hook's valid range. However, __mark_reg_s32_range() intersects the new range with the register's existing bounds using max_t()/min_t() rather than replacing them.

If the destination register carries stale bounds from a prior instruction (e.g. BPF_MOV64_IMM), the intersection can produce a range narrower than reality.

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The verifier then believes it knows the register's exact value, while at runtime the actual hook return value is loaded, creating a verifier/runtime mismatch that can be used to bypass BPF memory safety checks.

The else branch already calls mark_reg_unknown() to reset register state before any narrowing. Apply the same reset in the is_retval path so stale bounds are cleared before __mark_reg_s32_range() intersects.

CVSS

Probabilidad de explotación (EPSS)

EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).

🎯 Técnicas ATT&CK

Cómo se explota esta vulnerabilidad y qué consigue el atacante, en el lenguaje de MITRE ATT&CK.

Vulnerabilidad local del kernel Linux (AV:L, PR:L) que permite bypass de verificaciones de seguridad BPF para alcanzar ejecución de código con privilegios elevados (S:C, I:H, A:H).

Inferido por nuestro agente de análisis a partir de la descripción oficial, el vector CVSS y la CWE, y comprobado por un supervisor. Puede contener errores.

🛡️ Mitigaciones ATT&CK que cubren estas técnicas

Tecnologías afectadas (1)

⚠ Inferidas por IA a partir de la descripción — NVD aún no ha analizado esta CVE; no son CPE verificados.

Referencias

JSON original (NVD)

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{
  "id": "CVE-2026-72111",
  "cveTags": [],
  "metrics": {
    "cvssMetricV31": [
      {
        "type": "Secondary",
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "cvssData": {
          "scope": "CHANGED",
          "version": "3.1",
          "baseScore": 8.8,
          "attackVector": "LOCAL",
          "baseSeverity": "HIGH",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H",
          "integrityImpact": "HIGH",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "availabilityImpact": "HIGH",
          "privilegesRequired": "LOW",
          "confidentialityImpact": "HIGH"
        },
        "impactScore": 6,
        "exploitabilityScore": 2
      }
    ]
  },
  "affected": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "affectedData": [
        {
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "product": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "5d99e198be279045e6ecefe220f5c52f8ce9bfd5",
              "lessThan": "bde92f65042ec14389782dd223f706bf6b59ce5d",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "5d99e198be279045e6ecefe220f5c52f8ce9bfd5",
              "lessThan": "0993dc5fc619c0b25ab1310cb11d65e78351c0fe",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "5d99e198be279045e6ecefe220f5c52f8ce9bfd5",
              "lessThan": "5a55f9aecc08990940e70f0c7048a80850c5a16a",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "5d99e198be279045e6ecefe220f5c52f8ce9bfd5",
              "lessThan": "5e0b273e0a62cc04ec338c7b502797c66c2ed42a",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "1050727d83e70449991c29dd1cf29fe936a63da3",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "27ca3e20fe80be85a92b10064dfeb56cb2564b1c",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "6.10.13",
              "lessThan": "6.11",
              "versionType": "semver"
            },
            {
              "status": "affected",
              "version": "6.11.2",
              "lessThan": "6.12",
              "versionType": "semver"
            }
          ],
          "programFiles": [
            "kernel/bpf/verifier.c"
          ],
          "defaultStatus": "unaffected"
        },
        {
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "product": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.12"
            },
            {
              "status": "unaffected",
              "version": "0",
              "lessThan": "6.12",
              "versionType": "semver"
            },
            {
              "status": "unaffected",
              "version": "6.12.103",
              "versionType": "semver",
              "lessThanOrEqual": "6.12.*"
            },
            {
              "status": "unaffected",
              "version": "6.18.40",
              "versionType": "semver",
              "lessThanOrEqual": "6.18.*"
            },
            {
              "status": "unaffected",
              "version": "7.1.5",
              "versionType": "semver",
              "lessThanOrEqual": "7.1.*"
            },
            {
              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix",
              "lessThanOrEqual": "*"
            }
          ],
          "programFiles": [
            "kernel/bpf/verifier.c"
          ],
          "defaultStatus": "affected"
        }
      ]
    }
  ],
  "published": "2026-08-15T06:21:25.447",
  "references": [
    {
      "url": "https://git.kernel.org/stable/c/0993dc5fc619c0b25ab1310cb11d65e78351c0fe",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/5a55f9aecc08990940e70f0c7048a80850c5a16a",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/5e0b273e0a62cc04ec338c7b502797c66c2ed42a",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/bde92f65042ec14389782dd223f706bf6b59ce5d",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "vulnStatus": "Received",
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Reset register bounds before narrowing retval range in check_mem_access()\n\nWhen the BPF verifier processes a context load of an LSM hook return\nvalue, it calls __mark_reg_s32_range() to narrow the register to the\nhook's valid range. However, __mark_reg_s32_range() intersects the new\nrange with the register's existing bounds using max_t()/min_t() rather\nthan replacing them.\n\nIf the destination register carries stale bounds from a prior instruction\n(e.g. BPF_MOV64_IMM), the intersection can produce a range narrower than\nreality. The verifier then believes it knows the register's exact value,\nwhile at runtime the actual hook return value is loaded, creating a\nverifier/runtime mismatch that can be used to bypass BPF memory safety\nchecks.\n\nThe else branch already calls mark_reg_unknown() to reset register state\nbefore any narrowing. Apply the same reset in the is_retval path so\nstale bounds are cleared before __mark_reg_s32_range() intersects."
    }
  ],
  "lastModified": "2026-08-17T06:18:10.280",
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}