{
  "schema_version": "1.6.1",
  "id": "RPI-CVE-2026-89587",
  "modified": "2026-10-09T11:39:44Z",
  "upstream": [
    "CVE-2026-89587"
  ],
  "published": "2026-09-11T19:47:07Z",
  "summary": "ACPI: pfr_update: fix stack buffer overflow in query_capability()",
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nACPI: pfr_update: fix stack buffer overflow in query_capability()\n\nquery_capability() copies four ACPI buffer objects returned by the\nfirmware _DSM into fixed-size u8[16] fields in struct\npfru_update_cap_info using memcpy with the firmware-supplied length:\n\n  memcpy(&cap_hdr->code_type,\n         elements[CAP_CODE_TYPE_IDX].buffer.pointer,\n         elements[CAP_CODE_TYPE_IDX].buffer.length);\n\nThe same pattern repeats for drv_type, platform_id, and oem_id.\nIf the firmware returns buffer.length > 16 for any of these fields,\nmemcpy writes past the destination array.\n\nstruct pfru_update_cap_info is stack-allocated in pfru_ioctl().\n\nConfirmed with KASAN on 7.2-rc6: three stack-out-of-bounds reports\nare generated when a DSM returns 64-byte buffers, with writes reaching\n44 bytes past the end of cap_hdr's [64, 156) frame window into\nadjacent stack redzones.\n\nIntroduce a helper pointer to out_obj->package.elements and use it\nto validate each buffer length against its destination field size\nbefore copying, returning -EINVAL if the firmware supplies an\noversized buffer.",
  "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": "6.1.188",
            "compiled_filter": false
          }
        }
      }
    }
  ],
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://www.cve.org/CVERecord?id=CVE-2026-89587"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/d3af83e327565a9444cebc0db714cb837e493046"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/c5a31b4e7e37c92550be9a2edf51ca853a4d251a"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/a2151624b55029dad0ca7efd17fb83a0461c8843"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/6d4ed2fd022bc862b156e53aae163b61259e1caa"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/15d2b7f38f95d28652170344f39ee492c55e567c"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/ced45be0073a8a31b30b4a7f68cd3a15734515de"
    }
  ],
  "database_specific": {
    "source": "https://git.kernel.org/pub/scm/linux/security/vulns.git",
    "upstream_modified": "2026-09-14T12:06:03Z",
    "severity": {
      "source": "kernel CNA",
      "cvss_v3_score": 7.8,
      "cvss_v3_severity": "High",
      "scenario": "AV:L - The overflow is reached only via local ioctl(PFRU_IOC_QUERY_CAP) or write() on /dev/acpi_pfr_updateN (pfru_ioctl/pfru_write \u2192 query_capability). No network, Bluetooth, USB, or packet path evaluates this ACPI _DSM copy.\nAC:L - A single ioctl or write deterministically copies firmware-supplied _DSM buffer lengths into 16-byte stack fields; KASAN reproduced 64-byte DSM buffers writing 44 bytes past cap_hdr. No race or attacker-uncontrollable memory layout is required.\nPR:L - The ioctl/write path has no capable() or namespace check; access is only DAC on the misc device. Although pfrut checks uid 0 and devtmpfs defaults to 0600, Intel PFRU servers reasonably grant /dev/acpi_pfr_updateN to a firmware-management account or container, so privileges are Low.\nUI:N - The attacker opens the device and issues PFRU_IOC_QUERY_CAP or write() themselves; no separate victim action such as mounting a filesystem or opening a hostile file is required.\nS:U - The overflow corrupts the calling task's kernel stack inside the host kernel. This is local privilege escalation within one security authority, not a VM escape, IOMMU bypass, or sandbox breakout.\nC:H - Firmware-controlled memcpy overflows four u8[16] stack fields and adjacent frame state (KASAN: 44 bytes past cap_hdr), which per kernel guidance is memory corruption leverageable for arbitrary kernel memory disclosure.\nI:H - This is a kernel stack buffer overflow of firmware-controlled length and contents into stack-allocated struct pfru_update_cap_info, overwriting saved registers and the return address and enabling control-flow hijacking.\nA:H - The same out-of-bounds stack writes were confirmed by KASAN and can oops, trip the stack protector, or panic the kernel; the ioctl can be repeated to deny availability."
    }
  }
}