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CVE-2026-74556

Estado: RecibidaCrítica (9.8)—

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

scsi: libiscsi_tcp: Bound SCSI Response data segment to the connection buffer

iscsi_tcp_hdr_dissect() receives the data segment of several PDU types into the fixed-size conn->data buffer, which is allocated for ISCSI_DEF_MAX_RECV_SEG_LEN (8192) bytes. For the LOGIN_RSP, TEXT_RSP, REJECT and ASYNC_EVENT opcodes the dissect path already rejects a PDU whose DataSegmentLength exceeds that buffer.

The SCSI Command Response (ISCSI_OP_SCSI_CMD_RSP) path also copies its data segment (sense/response data) into conn->data via iscsi_tcp_data_recv_prep(), but it does so without the same check.

Leer descripción completaMostrar menos

The only upstream bound on in.datalen is conn->max_recv_dlength, the initiator's advertised MaxRecvDataSegmentLength, which is commonly negotiated well above 8192 (open-iscsi defaults to 262144). A target that returns a SCSI Response with a DataSegmentLength between 8193 and max_recv_dlength therefore overflows the 8192-byte conn->data buffer.

Once the same bound applies, ISCSI_OP_SCSI_CMD_RSP is handled exactly like those responses: bound the data segment, receive it into conn->data when present, and otherwise complete the PDU with no data. Fold the opcode into that case group rather than duplicating the check.

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 remota en kernel Linux sin autenticación (AV:N PR:N) que causa desbordamiento de buffer en iscsi_tcp al recibir respuesta SCSI malformada; impacta disponibilidad (DoS/kernel crash) y posible escalada de 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

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)

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{
  "id": "CVE-2026-74556",
  "cveTags": [],
  "metrics": {
    "cvssMetricV31": [
      {
        "type": "Secondary",
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "cvssData": {
          "scope": "UNCHANGED",
          "version": "3.1",
          "baseScore": 9.8,
          "attackVector": "NETWORK",
          "baseSeverity": "CRITICAL",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
          "integrityImpact": "HIGH",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "availabilityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "confidentialityImpact": "HIGH"
        },
        "impactScore": 5.9,
        "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": [
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              "status": "affected",
              "version": "a081c13e39b5c17052a7b46fafa61019c4c110ff",
              "lessThan": "a51812842084fd390590ab8dc0431f10c73ddc56",
              "versionType": "git"
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            {
              "status": "affected",
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              "versionType": "git"
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            {
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              "versionType": "git"
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            {
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              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "a081c13e39b5c17052a7b46fafa61019c4c110ff",
              "lessThan": "72815741715bd41556dac5eeb068bf0f8af06ee7",
              "versionType": "git"
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              "versionType": "git"
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          ],
          "programFiles": [
            "drivers/scsi/libiscsi_tcp.c"
          ],
          "defaultStatus": "unaffected"
        },
        {
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "product": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "2.6.29"
            },
            {
              "status": "unaffected",
              "version": "0",
              "lessThan": "2.6.29",
              "versionType": "semver"
            },
            {
              "status": "unaffected",
              "version": "5.10.265",
              "versionType": "semver",
              "lessThanOrEqual": "5.10.*"
            },
            {
              "status": "unaffected",
              "version": "5.15.216",
              "versionType": "semver",
              "lessThanOrEqual": "5.15.*"
            },
            {
              "status": "unaffected",
              "version": "6.1.183",
              "versionType": "semver",
              "lessThanOrEqual": "6.1.*"
            },
            {
              "status": "unaffected",
              "version": "6.6.151",
              "versionType": "semver",
              "lessThanOrEqual": "6.6.*"
            },
            {
              "status": "unaffected",
              "version": "6.12.103",
              "versionType": "semver",
              "lessThanOrEqual": "6.12.*"
            },
            {
              "status": "unaffected",
              "version": "6.18.44",
              "versionType": "semver",
              "lessThanOrEqual": "6.18.*"
            },
            {
              "status": "unaffected",
              "version": "7.1.8",
              "versionType": "semver",
              "lessThanOrEqual": "7.1.*"
            },
            {
              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix",
              "lessThanOrEqual": "*"
            }
          ],
          "programFiles": [
            "drivers/scsi/libiscsi_tcp.c"
          ],
          "defaultStatus": "affected"
        }
      ]
    }
  ],
  "published": "2026-08-15T13:18:01.047",
  "references": [
    {
      "url": "https://git.kernel.org/stable/c/084af0253673425ce2ae62e3c7f74f0dd023711b",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/72815741715bd41556dac5eeb068bf0f8af06ee7",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/a51812842084fd390590ab8dc0431f10c73ddc56",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/a8f94cc9f0e5759252551be3a172960c57f21f54",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
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      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
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      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
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      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/f1a3a51fc5dba0e99532379665069f1700da6b44",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "vulnStatus": "Received",
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nscsi: libiscsi_tcp: Bound SCSI Response data segment to the connection buffer\n\niscsi_tcp_hdr_dissect() receives the data segment of several PDU types\ninto the fixed-size conn->data buffer, which is allocated for\nISCSI_DEF_MAX_RECV_SEG_LEN (8192) bytes.  For the LOGIN_RSP, TEXT_RSP,\nREJECT and ASYNC_EVENT opcodes the dissect path already rejects a PDU\nwhose DataSegmentLength exceeds that buffer.\n\nThe SCSI Command Response (ISCSI_OP_SCSI_CMD_RSP) path also copies its\ndata segment (sense/response data) into conn->data via\niscsi_tcp_data_recv_prep(), but it does so without the same check.  The\nonly upstream bound on in.datalen is conn->max_recv_dlength, the\ninitiator's advertised MaxRecvDataSegmentLength, which is commonly\nnegotiated well above 8192 (open-iscsi defaults to 262144).  A target\nthat returns a SCSI Response with a DataSegmentLength between 8193 and\nmax_recv_dlength therefore overflows the 8192-byte conn->data buffer.\n\nOnce the same bound applies, ISCSI_OP_SCSI_CMD_RSP is handled exactly\nlike those responses: bound the data segment, receive it into conn->data\nwhen present, and otherwise complete the PDU with no data.  Fold the\nopcode into that case group rather than duplicating the check."
    }
  ],
  "lastModified": "2026-08-19T17:21:10.753",
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}