CVE-2026-89763

Estado: RecibidaAlta (7.8)—

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

KEYS: trusted: Fix TPM teardown ordering

trusted_tpm_exit() drops the TPM chip reference and frees the digest array before unregistering the trusted key type. key_type_lookup() holds key_types_sem for reading until the key operation finishes, while unregister_key_type() takes it for writing. It therefore provides the synchronization point that must precede backend teardown.

The current order permits this interleaving:

CPU 1 can consequently dereference the freed digest array. The chip can also be released before callbacks stop using it.

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Move unregister_key_type() before releasing either resource. This stops new lookups and waits for in-flight key operations to finish before the backend state is destroyed.

Detalles técnicos trazas, registros y código del informe original

  CPU 0                              CPU 1
  trusted_tpm_exit()                 key_type_lookup("trusted")
    put_device(&chip->dev)             trusted_tpm_seal()
    kfree(digests)                       pcrlock()
    unregister_key_type()                  tpm_pcr_extend(..., digests)

KASAN reported:

  BUG: KASAN: slab-use-after-free in tpm_pcr_extend+0x1f0/0x200
  Read of size 2 at addr ffff88810872d000 by task poc/89
  Call Trace:
    tpm_pcr_extend+0x1f0/0x200
    pcrlock+0x42/0x70 [trusted]
    trusted_tpm_seal+0x1b6/0x570 [trusted]
    trusted_instantiate+0x293/0x340 [trusted]
    __key_instantiate_and_link+0xb2/0x2b0
    __key_create_or_update+0x61e/0xb50
    __do_sys_add_key+0x1b8/0x310
  Allocated by task 88:
    __kmalloc_noprof+0x1a7/0x490
    do_one_initcall+0xa1/0x390
    do_init_module+0x2df/0x840
  Freed by task 90:
    kfree+0x131/0x3c0
    trusted_tpm_exit+0x59/0xa0 [trusted]
    __do_sys_delete_module+0x346/0x510

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: 0.12%
Percentil entre todas las CVEs puntuadas: 2
Fecha de la puntuación: 5/10/2026

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 principalT1499.004 Application or System Exploitationimpact75 %
Impacto secundarioT1565.001 Stored Data Manipulationimpact60 %

AV:L/PR:L sin UI permite escalada local. Use-after-free en TPM permite DoS por null pointer/crash o corrupción de memoria de claves TPM (integridad).

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

Threat Intelligence Program Restrict File and Directory Permissions Remote Data Storage Filter Network Traffic Execution Prevention Encrypt Sensitive Information

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-2026-89763",
  "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": "0b6cf6b97b7ef1fa3c7fefab0cac897a1c4a3400",
              "lessThan": "3d67b4acbfc7af331d887a8efc04bef6573b8a7a",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "0b6cf6b97b7ef1fa3c7fefab0cac897a1c4a3400",
              "lessThan": "753c978f2400f9783eb524842a975d3ac950d511",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "0b6cf6b97b7ef1fa3c7fefab0cac897a1c4a3400",
              "lessThan": "2f7541afbc57fe9d26769a22c31d8ce8790c9a19",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "0b6cf6b97b7ef1fa3c7fefab0cac897a1c4a3400",
              "lessThan": "5e2d672280d97d83de43031d93761b12dadd7b8a",
              "versionType": "git"
            }
          ],
          "programFiles": [
            "security/keys/trusted-keys/trusted_tpm1.c"
          ],
          "defaultStatus": "unaffected"
        },
        {
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "product": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "5.1"
            },
            {
              "status": "unaffected",
              "version": "0",
              "lessThan": "5.1",
              "versionType": "semver"
            },
            {
              "status": "unaffected",
              "version": "6.12.111",
              "versionType": "semver",
              "lessThanOrEqual": "6.12.*"
            },
            {
              "status": "unaffected",
              "version": "6.18.50",
              "versionType": "semver",
              "lessThanOrEqual": "6.18.*"
            },
            {
              "status": "unaffected",
              "version": "7.2.4",
              "versionType": "semver",
              "lessThanOrEqual": "7.2.*"
            },
            {
              "status": "unaffected",
              "version": "7.3-rc1",
              "versionType": "original_commit_for_fix",
              "lessThanOrEqual": "*"
            }
          ],
          "programFiles": [
            "security/keys/trusted-keys/trusted_tpm1.c"
          ],
          "defaultStatus": "affected"
        }
      ]
    }
  ],
  "published": "2026-09-11T20:20:07.523",
  "references": [
    {
      "url": "https://git.kernel.org/stable/c/2f7541afbc57fe9d26769a22c31d8ce8790c9a19",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/3d67b4acbfc7af331d887a8efc04bef6573b8a7a",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/5e2d672280d97d83de43031d93761b12dadd7b8a",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/753c978f2400f9783eb524842a975d3ac950d511",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "vulnStatus": "Received",
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nKEYS: trusted: Fix TPM teardown ordering\n\ntrusted_tpm_exit() drops the TPM chip reference and frees the digest\narray before unregistering the trusted key type. key_type_lookup()\nholds key_types_sem for reading until the key operation finishes, while\nunregister_key_type() takes it for writing. It therefore provides the\nsynchronization point that must precede backend teardown.\n\nThe current order permits this interleaving:\n\n  CPU 0                              CPU 1\n  trusted_tpm_exit()                 key_type_lookup(\"trusted\")\n    put_device(&chip->dev)             trusted_tpm_seal()\n    kfree(digests)                       pcrlock()\n    unregister_key_type()                  tpm_pcr_extend(..., digests)\n\nCPU 1 can consequently dereference the freed digest array. The chip can\nalso be released before callbacks stop using it.\n\nKASAN reported:\n\n  BUG: KASAN: slab-use-after-free in tpm_pcr_extend+0x1f0/0x200\n  Read of size 2 at addr ffff88810872d000 by task poc/89\n  Call Trace:\n    tpm_pcr_extend+0x1f0/0x200\n    pcrlock+0x42/0x70 [trusted]\n    trusted_tpm_seal+0x1b6/0x570 [trusted]\n    trusted_instantiate+0x293/0x340 [trusted]\n    __key_instantiate_and_link+0xb2/0x2b0\n    __key_create_or_update+0x61e/0xb50\n    __do_sys_add_key+0x1b8/0x310\n  Allocated by task 88:\n    __kmalloc_noprof+0x1a7/0x490\n    do_one_initcall+0xa1/0x390\n    do_init_module+0x2df/0x840\n  Freed by task 90:\n    kfree+0x131/0x3c0\n    trusted_tpm_exit+0x59/0xa0 [trusted]\n    __do_sys_delete_module+0x346/0x510\n\nMove unregister_key_type() before releasing either resource. This stops\nnew lookups and waits for in-flight key operations to finish before the\nbackend state is destroyed."
    }
  ],
  "lastModified": "2026-09-21T14:17:26.447",
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}