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CVE-2026-63952

Estado: Pendiente de análisisAlta (8.4)—

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

memfd: deny writeable mappings when implying SEAL_WRITE

When SEAL_EXEC is added, SEAL_WRITE is implied to make W^X. But the implied seal is set after the check that makes sure the memfd can not have any writable mappings. This means one can use SEAL_EXEC to apply SEAL_WRITE while having writeable mappings.

This breaks the contract that SEAL_WRITE provides and can be used by an attacker to pass a memfd that appears to be write sealed but can still be modified arbitrarily.

Fix this by adding the implied seals before the call for mapping_deny_writable() is done.

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 que permite eludir restricciones de escritura (SEAL_WRITE) en memfd mediante SEAL_EXEC, escalando privil. Permite modificación arbitraria de memoria desde proceso sin privilegios.

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

User TrainingThreat Intelligence ProgramRestrict File and Directory PermissionsRemote Data StorageExecution PreventionBehavior Prevention on Endpoint

Tecnologías afectadas (1)

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

Linux — Linux KernelAI

Referencias

JSON original (NVD)

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{
  "id": "CVE-2026-63952",
  "cveTags": [],
  "metrics": {
    "cvssMetricV31": [
      {
        "type": "Secondary",
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "cvssData": {
          "scope": "CHANGED",
          "version": "3.1",
          "baseScore": 8.4,
          "attackVector": "LOCAL",
          "baseSeverity": "HIGH",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N",
          "integrityImpact": "HIGH",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "availabilityImpact": "NONE",
          "privilegesRequired": "LOW",
          "confidentialityImpact": "HIGH"
        },
        "impactScore": 5.8,
        "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": "c4f75bc8bd6b3d62665e1f5400c419540edb5601",
              "lessThan": "b3f4f82d1315f1439059a83d1c22c51a5b43d99e",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "c4f75bc8bd6b3d62665e1f5400c419540edb5601",
              "lessThan": "3be2a24f7f72ad7321ed6ad1715b956a4527bcf4",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "c4f75bc8bd6b3d62665e1f5400c419540edb5601",
              "lessThan": "0995d1f79aed8ccbf62056189dd53fd19726ea08",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "c4f75bc8bd6b3d62665e1f5400c419540edb5601",
              "lessThan": "555702282d4536a865dfffb1cd4f6028f196e7e8",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "c4f75bc8bd6b3d62665e1f5400c419540edb5601",
              "lessThan": "3b041514cb6eae45869b020f743c14d983363222",
              "versionType": "git"
            }
          ],
          "programFiles": [
            "mm/memfd.c"
          ],
          "defaultStatus": "unaffected"
        },
        {
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "product": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.3"
            },
            {
              "status": "unaffected",
              "version": "0",
              "lessThan": "6.3",
              "versionType": "semver"
            },
            {
              "status": "unaffected",
              "version": "6.6.143",
              "versionType": "semver",
              "lessThanOrEqual": "6.6.*"
            },
            {
              "status": "unaffected",
              "version": "6.12.93",
              "versionType": "semver",
              "lessThanOrEqual": "6.12.*"
            },
            {
              "status": "unaffected",
              "version": "6.18.35",
              "versionType": "semver",
              "lessThanOrEqual": "6.18.*"
            },
            {
              "status": "unaffected",
              "version": "7.0.12",
              "versionType": "semver",
              "lessThanOrEqual": "7.0.*"
            },
            {
              "status": "unaffected",
              "version": "7.1",
              "versionType": "original_commit_for_fix",
              "lessThanOrEqual": "*"
            }
          ],
          "programFiles": [
            "mm/memfd.c"
          ],
          "defaultStatus": "affected"
        }
      ]
    }
  ],
  "published": "2026-07-19T16:17:13.950",
  "references": [
    {
      "url": "https://git.kernel.org/stable/c/0995d1f79aed8ccbf62056189dd53fd19726ea08",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/3b041514cb6eae45869b020f743c14d983363222",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/3be2a24f7f72ad7321ed6ad1715b956a4527bcf4",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/555702282d4536a865dfffb1cd4f6028f196e7e8",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/b3f4f82d1315f1439059a83d1c22c51a5b43d99e",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "vulnStatus": "Awaiting Analysis",
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nmemfd: deny writeable mappings when implying SEAL_WRITE\n\nWhen SEAL_EXEC is added, SEAL_WRITE is implied to make W^X.  But the\nimplied seal is set after the check that makes sure the memfd can not have\nany writable mappings.  This means one can use SEAL_EXEC to apply\nSEAL_WRITE while having writeable mappings.\n\nThis breaks the contract that SEAL_WRITE provides and can be used by an\nattacker to pass a memfd that appears to be write sealed but can still be\nmodified arbitrarily.\n\nFix this by adding the implied seals before the call for\nmapping_deny_writable() is done."
    }
  ],
  "lastModified": "2026-07-27T17:44:23.777",
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}