Backup for Microsoft 365 — security advisory

{
  "id": "540649234fd807f21f7ce193b13583bf58d9bc70add671a12b2c8e50cbb5e1fe",
  "url": "https://www.cve.org/CVERecord?id=CVE-2025-64394",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "CVE-2025-64394",
    "summary": "A vulnerability allowing a low-privileged local user to write arbitrary files with SYSTEM privileges during the installation of Veeam Backup for Microsoft 365, which can lead to privilege escalation or denial of service.",
    "evidence": "cve:CVE-2025-64394",
    "products": [
      {
        "name": {
          "value": "Backup for Microsoft 365",
          "evidence": "/containers/cna/affected/0/product"
        },
        "prerequisites": [],
        "fixed_versions": [],
        "affected_versions": []
      }
    ],
    "severity": "medium",
    "structured": {
      "id": "CVE-2025-64394",
      "aliases": [
        "CVE-2025-64394"
      ],
      "metrics": [
        {
          "cvssV4_0": {
            "version": "4.0",
            "baseScore": 4.3,
            "baseSeverity": "MEDIUM",
            "vectorString": "CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:A/VC:N/VI:L/VA:H/SC:N/SI:N/SA:N"
          }
        }
      ],
      "affected": [
        {
          "vendor": "Veeam",
          "product": "Backup for Microsoft 365",
          "versions": [
            {
              "status": "affected",
              "version": "8.0",
              "versionType": "semver",
              "lessThanOrEqual": "8.6.0.1102"
            }
          ],
          "defaultStatus": "unaffected"
        }
      ],
      "modified": "2026-10-27T16:16:58.979Z",
      "provider": "cve",
      "references": [
        "https://www.veeam.com/kb4957"
      ],
      "provider_metadata": {
        "cna": {
          "orgId": "36234546-b8fa-4601-9d6f-f4e334aa8ea1",
          "shortName": "hackerone",
          "dateUpdated": "2026-10-27T16:16:58.979Z"
        }
      }
    },
    "related_cves": [
      {
        "value": "CVE-2025-64394",
        "evidence": "/cveMetadata/cveId"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/containers/cna/metrics"
  },
  "source_id": "core-cve",
  "document_id": 394440,
  "published_at": "2026-10-27T16:16:58.979+00:00"
}