{
  "schema_version": "1.6.1",
  "id": "RPI-CVE-2026-64086",
  "modified": "2026-10-09T11:39:44Z",
  "upstream": [
    "CVE-2026-64086"
  ],
  "published": "2026-07-19T15:41:06Z",
  "summary": "hwmon: (pmbus/adm1266) include PEC byte in pmbus_block_xfer read buffer",
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nhwmon: (pmbus/adm1266) include PEC byte in pmbus_block_xfer read buffer\n\nadm1266_pmbus_block_xfer() sets up the read transaction with\n\n\t.buf = data->read_buf,\n\t.len = ADM1266_PMBUS_BLOCK_MAX + 2,\n\nbut read_buf in struct adm1266_data is declared as\n\n\tu8 read_buf[ADM1266_PMBUS_BLOCK_MAX + 1];\n\nFor a max-length block response (length byte = 255 + up to 1 PEC\nbyte), the i2c controller is told to write 257 bytes into a 256-byte\nbuffer, putting one byte past the end of read_buf.  The same response\nalso makes the subsequent PEC compare\n\n\tif (crc != msgs[1].buf[msgs[1].buf[0] + 1])\n\nread a byte beyond the array.\n\nBump the read_buf declaration to ADM1266_PMBUS_BLOCK_MAX + 2 so the\nbuffer can hold the length byte, up to 255 payload bytes, and the PEC\nbyte the i2c_msg length already accounts for.",
  "severity": [
    {
      "type": "CVSS_V3",
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"
    }
  ],
  "affected": [
    {
      "package": {
        "ecosystem": "Raspberry Pi OS:12",
        "name": "linux"
      },
      "versions": [
        "1:6.1.47-1+rpt4"
      ],
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "linux-image-6.1.0-rpi3-rpi-2712",
            "binary_version": "1:6.1.47-1+rpt4"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi3-rpi-v6",
            "binary_version": "1:6.1.47-1+rpt4"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi3-rpi-v7",
            "binary_version": "1:6.1.47-1+rpt4"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi3-rpi-v7l",
            "binary_version": "1:6.1.47-1+rpt4"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi3-rpi-v8",
            "binary_version": "1:6.1.47-1+rpt4"
          }
        ]
      },
      "database_specific": {
        "per_version": {
          "1:6.1.47-1+rpt4": {
            "linux_commit": "655fc658a15ae7a6f37103754adb39ba52a9a14e",
            "upstream_version": "6.1.47",
            "assessment": "commit ancestry (strak rule)",
            "upstream_fixed": "6.1.175",
            "compiled_filter": false
          }
        }
      }
    }
  ],
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://www.cve.org/CVERecord?id=CVE-2026-64086"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/397d3f523bfff2f4e3dacf9b1339bd76dc207f78"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/472744f69d25a2d5111ad62f1d62579dce2c13c8"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/528a9f88e88502d0c2f2052a279415074cd83715"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/d94ceb16e55b6d8019ab069e357c76ac42f0ffbc"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/bd5be3fa5de6dbf61f1b3cec6b79c2c2f8065694"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/2279c342d94eca225bf9f301c8806a05a1c81619"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/a6c802145a8de0830bca803c6d415f7e9e683624"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/487566cb1ccdf3756fdd7bf8d875e612ff3169bb"
    }
  ],
  "database_specific": {
    "source": "https://git.kernel.org/pub/scm/linux/security/vulns.git",
    "upstream_modified": "2026-08-05T13:16:28Z",
    "severity": {
      "source": "kernel CNA",
      "cvss_v3_score": 7.8,
      "cvss_v3_severity": "High",
      "scenario": "AV:L - The vulnerable code is only reached through local kernel interfaces (debugfs GPIO dump at /sys/kernel/debug/gpio and root-only nvmem blackbox reads), not through any network protocol handler. The ADM1266 sits on an on-board I2C bus on server BMC hardware.\nAC:L - An attacker who controls the I2C bus response (malicious device, compromised ADM1266 firmware, or bus interposition on the BMC) can reliably force a 255-byte block reply whenever a victim triggers the block-transfer path, causing the one-byte overflow on demand.\nPR:L - The gpio debugfs entry is world-readable (0444) if debugfs is mounted and traversable, which occurs on some embedded BMC images without strict permissions; between requiring full init-namespace root and that lower bar, the less privileged path is plausible on misconfigured systems.\nUI:N - Exploitation does not require victim interaction beyond the attacker (or a compromised daemon) programmatically reading debugfs or nvmem; no mount, click, or plug-in action by an end user is needed.\nS:U - Impact is confined to kernel memory corruption within the BMC/host kernel security boundary; this is not a VM escape, IOMMU bypass, or cross-authority sandbox breakout.\nC:H - The PEC validation performs an out-of-bounds read past read_buf, and the one-byte heap overflow can corrupt adjacent kernel objects in ways that enable further memory disclosure primitives.\nI:H - A one-byte, attacker-controlled out-of-bounds write past the end of read_buf into adjacent heap memory can corrupt slab metadata or neighboring objects and be developed into arbitrary write or code-execution primitives.\nA:H - Corrupting adjacent heap objects via the out-of-bounds write can cause kernel oops, panic, or hang on the BMC, denying management-plane availability for the managed server."
    }
  }
}