CVE-2026-80544

Estado: RecibidaAlta (7.8)—

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

s390/zcrypt: Improve EP11 CPRB domain handling with ASN.1 parsing

The zcrypt_msgtype6_send_ep11_cprb() function uses fragile struct overlays to access and modify the domain field in the EP11 CPRB payload, creating maintainability and security concerns: 1. Struct overlay approach (pld_hdr) assumes fixed payload structure and doesn't validate the actual ASN.1 encoding. 2. Complex length format detection logic is error-prone and doesn't properly validate bounds at each parsing step. 3. Direct struct member access bypasses proper ASN.1 validation.

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Fix by replacing struct overlays with explicit ASN.1 parsing that validates each field (payload tag/length, function tag/length/value, optional domain tag/length/value) with proper bounds checking at every step. Add asn1_int_encode() helper function to safely write integer values with correct endianness conversion. This makes the code consistent with the validation pattern introduced with the rework of the xcrb_msg_to_type6_ep11cprb_msgx() function.

CVSS

Versión: 3.1
Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Puntuación base: 7.8

Probabilidad de explotación (EPSS)

Probabilidad de explotación en los próximos 30 días: 0.19%
Percentil entre todas las CVEs puntuadas: 8
Fecha de la puntuación: 6/10/2026

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.

ExplotaciónT1068 Exploitation for Privilege Escalationprivilege escalation85 %
Impacto principalT1059 Command and Scripting Interpreterexecution75 %
Impacto secundarioT1565.001 Stored Data Manipulationimpact70 %

Vuln. local (AV:L/PR:L) en kernel s390/zcrypt sin UI. Acceso a lectura/escritura de memoria mediante overlay de structs permite escala de privilegios (C:H/I:H). Ejecución de código y manipulación de datos en CPRB.

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

Execution Prevention Threat Intelligence Program Restrict Web-Based Content Restrict File and Directory Permissions Privileged Account Management Remote Data Storage

Tecnologías afectadas (1)

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

Linux — Linux Kernel^AI

Referencias

JSON original (NVD)

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{
  "id": "CVE-2026-80544",
  "cveTags": [],
  "metrics": {
    "cvssMetricV31": [
      {
        "type": "Secondary",
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "cvssData": {
          "scope": "UNCHANGED",
          "version": "3.1",
          "baseScore": 7.8,
          "attackVector": "LOCAL",
          "baseSeverity": "HIGH",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
          "integrityImpact": "HIGH",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "availabilityImpact": "HIGH",
          "privilegesRequired": "LOW",
          "confidentialityImpact": "HIGH"
        },
        "impactScore": 5.9,
        "exploitabilityScore": 1.8
      }
    ]
  },
  "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": "e2c6d91eb8b1533753755f07803e47eceed263d0",
              "lessThan": "db21b2cf6dd0af5ffd08931e0a9fcda5a0473220",
              "versionType": "git"
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            {
              "status": "affected",
              "version": "e2c6d91eb8b1533753755f07803e47eceed263d0",
              "lessThan": "0864a163783bff109b548266921829ea794edc93",
              "versionType": "git"
            }
          ],
          "programFiles": [
            "drivers/s390/crypto/zcrypt_msgtype6.c"
          ],
          "defaultStatus": "unaffected"
        },
        {
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "product": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "7.1"
            },
            {
              "status": "unaffected",
              "version": "0",
              "lessThan": "7.1",
              "versionType": "semver"
            },
            {
              "status": "unaffected",
              "version": "7.1.10",
              "versionType": "semver",
              "lessThanOrEqual": "7.1.*"
            },
            {
              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix",
              "lessThanOrEqual": "*"
            }
          ],
          "programFiles": [
            "drivers/s390/crypto/zcrypt_msgtype6.c"
          ],
          "defaultStatus": "affected"
        }
      ]
    }
  ],
  "published": "2026-08-26T15:17:08.763",
  "references": [
    {
      "url": "https://git.kernel.org/stable/c/0864a163783bff109b548266921829ea794edc93",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/db21b2cf6dd0af5ffd08931e0a9fcda5a0473220",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "vulnStatus": "Received",
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ns390/zcrypt: Improve EP11 CPRB domain handling with ASN.1 parsing\n\nThe zcrypt_msgtype6_send_ep11_cprb() function uses fragile struct\noverlays to access and modify the domain field in the EP11 CPRB\npayload, creating maintainability and security concerns:\n1. Struct overlay approach (pld_hdr) assumes fixed payload structure\n   and doesn't validate the actual ASN.1 encoding.\n2. Complex length format detection logic is error-prone and doesn't\n   properly validate bounds at each parsing step.\n3. Direct struct member access bypasses proper ASN.1 validation.\n\nFix by replacing struct overlays with explicit ASN.1 parsing that\nvalidates each field (payload tag/length, function tag/length/value,\noptional domain tag/length/value) with proper bounds checking at every\nstep. Add asn1_int_encode() helper function to safely write integer\nvalues with correct endianness conversion. This makes the code\nconsistent with the validation pattern introduced with the rework of\nthe xcrb_msg_to_type6_ep11cprb_msgx() function."
    }
  ],
  "lastModified": "2026-08-27T06:17:35.497",
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}