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CVE-2026-89632

Estado: RecibidaAlta (8.2)—

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

smb: client: fix use-before-check of ReparseDataLength in reparse_buf_ptr()

reparse_buf_ptr() reads buf->ReparseDataLength before checking that count covers the full fixed header:

struct reparse_data_buffer has ReparseDataLength at offset 4. If a server returns OutputCount < 6, the read at offset 4-5 reaches past the end of the received data. The off+count bounds against iov_len were already validated, but that does not protect against count being smaller than sizeof(*buf).

Split the check: verify count >= sizeof(*buf) before reading ReparseDataLength, then verify count covers the data region.

Detalles técnicos trazas, registros y código del informe original
    buf = (struct reparse_data_buffer *)((u8 *)io + off);
    len = sizeof(*buf);                          /* 8 bytes */
    rdlen = le16_to_cpu(buf->ReparseDataLength); /* offset 4, 2 bytes */

    if (count < len || count < rdlen + len)      /* check comes after */

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 en SMB client kernel remota (AV:N/AC:L/PR:N) que permite DoS por lectura fuera de límites. Acceso a datos en memoria kernel y potencial crash del servidor.

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

Filter Network TrafficVulnerability ScanningPrivileged Account ManagementNetwork SegmentationLimit Access to Resource Over NetworkApplication Isolation and Sandboxing

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)

Mostrar
{
  "id": "CVE-2026-89632",
  "cveTags": [],
  "metrics": {
    "cvssMetricV31": [
      {
        "type": "Secondary",
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "cvssData": {
          "scope": "UNCHANGED",
          "version": "3.1",
          "baseScore": 8.2,
          "attackVector": "NETWORK",
          "baseSeverity": "HIGH",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H",
          "integrityImpact": "NONE",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "availabilityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "confidentialityImpact": "LOW"
        },
        "impactScore": 4.2,
        "exploitabilityScore": 3.9
      }
    ]
  },
  "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": "a158bb66b1373866d9fd5997565a58a573085539",
              "lessThan": "711cf71300d7992f450600df8864917d3538679f",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "a158bb66b1373866d9fd5997565a58a573085539",
              "lessThan": "05f78e6cf34ea3a285053bd5999e08e8ac298bd5",
              "versionType": "git"
            }
          ],
          "programFiles": [
            "fs/smb/client/smb2inode.c"
          ],
          "defaultStatus": "unaffected"
        },
        {
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "product": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.6.32",
              "lessThan": "7.2.4",
              "versionType": "semver"
            },
            {
              "status": "affected",
              "version": "6.6.32",
              "lessThan": "7.3-rc1",
              "versionType": "semver"
            }
          ],
          "programFiles": [
            "fs/smb/client/smb2inode.c"
          ],
          "defaultStatus": "unaffected"
        }
      ]
    }
  ],
  "published": "2026-09-11T20:19:48.763",
  "references": [
    {
      "url": "https://git.kernel.org/stable/c/05f78e6cf34ea3a285053bd5999e08e8ac298bd5",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/711cf71300d7992f450600df8864917d3538679f",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "vulnStatus": "Received",
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nsmb: client: fix use-before-check of ReparseDataLength in reparse_buf_ptr()\n\nreparse_buf_ptr() reads buf->ReparseDataLength before checking that\ncount covers the full fixed header:\n\n    buf = (struct reparse_data_buffer *)((u8 *)io + off);\n    len = sizeof(*buf);                          /* 8 bytes */\n    rdlen = le16_to_cpu(buf->ReparseDataLength); /* offset 4, 2 bytes */\n\n    if (count < len || count < rdlen + len)      /* check comes after */\n\nstruct reparse_data_buffer has ReparseDataLength at offset 4.  If a\nserver returns OutputCount < 6, the read at offset 4-5 reaches past\nthe end of the received data.  The off+count bounds against iov_len\nwere already validated, but that does not protect against count being\nsmaller than sizeof(*buf).\n\nSplit the check: verify count >= sizeof(*buf) before reading\nReparseDataLength, then verify count covers the data region."
    }
  ],
  "lastModified": "2026-09-13T07:17:28.300",
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}