InsydeH2O IHISI SMM is vulnerable to unsafe memory write operations

{
  "id": "82d31e968c531ef15473dccebc32c8ae75af992b40997646f8dbc36bf2286a18",
  "url": "https://kb.cert.org/vuls/id/553437",
  "method": "llm",
  "payload": {
    "kind": "advisory",
    "title": "InsydeH2O IHISI SMM is vulnerable to unsafe memory write operations",
    "summary": "A vulnerability in an HP-custom SMM handler can let an attacker with OS kernel privileges read or write arbitrary physical memory, including SMRAM. The note identifies InsydeH2O Kernel version 5.5 or earlier as affected; users are directed to HP security bulletins to check whether their systems are affected.",
    "evidence": "An Out-of-bounds Write vulnerability in the InsydeH2O IHISI software used by HP PC BIOS can allow a local attacker with OS kernel privileges to perform arbitrary physical memory writes, including writes to System Management RAM (SMRAM).",
    "products": [
      {
        "name": {
          "value": "InsydeH2O Kernel",
          "evidence": "The affected system uses InsydeH2O Kernel version 5.5 or earlier."
        },
        "prerequisites": [
          {
            "value": "local attacker with OS kernel privileges",
            "evidence": "An Out-of-bounds Write vulnerability in the InsydeH2O IHISI software used by HP PC BIOS can allow a local attacker with OS kernel privileges to perform arbitrary physical memory writes, including writes to System Management RAM (SMRAM)."
          }
        ],
        "fixed_versions": [],
        "affected_versions": [
          {
            "value": "version 5.5 or earlier",
            "evidence": "The affected system uses InsydeH2O Kernel version 5.5 or earlier."
          }
        ]
      }
    ],
    "severity": "unknown",
    "fixed_cves": [],
    "related_cves": [
      {
        "value": "CVE-2026-12855",
        "evidence": "CVE-2026-12855: An Out-of-bounds Write vulnerability in the H19WMIHandlerSmm module"
      }
    ],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "official-cert-cc-vulnerability-notes",
  "document_id": 23370,
  "published_at": "2026-10-01T14:33:19.418+00:00"
}