Path traversal via unvalidated instance name in backup tarball restore enables root file write / RCE

{
  "id": "aa5ad84468417cb528e679b4d5e0680faceb61c88524fb1280b53f99f394d83c",
  "url": "https://osv.dev/vulnerability/CVE-2026-66898",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "Path traversal via unvalidated instance name in backup tarball restore enables root file write / RCE",
    "summary": "A path traversal vulnerability in LXD allows an attacker to manipulate file system paths during backup import and restore operations. When importing or restoring a backup archive, LXD fails to validate instance and storage volume names contained within the archive metadata. An attacker can exploit this flaw by supplying a crafted backup archive with malicious instance or volume names containing path traversal sequences, potentially allowing file access or overwriting outside the designated restore directory.",
    "evidence": "osv:CVE-2026-66898",
    "products": [],
    "severity": "critical",
    "structured": {
      "id": "CVE-2026-66898",
      "aliases": [
        "CVE-2026-66898",
        "GHSA-m857-c7gc-c984"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/canonical/lxd",
              "type": "GIT",
              "events": [
                {
                  "introduced": "03aab09f5b5cbdada00c6539877dcf5932fcde98"
                },
                {
                  "fixed": "a55c9d0228552323d96cc330fb36f9471581c4ab"
                },
                {
                  "introduced": "1e1349e3cbf30c1b2ce74e531d4dd0fd52c45be1"
                },
                {
                  "fixed": "2101d7f6efdaa7762e6593c857cb524bfcd2859b"
                },
                {
                  "introduced": "be2e2d38c65555880689da833c93d1e9d55ae94d"
                },
                {
                  "fixed": "7d4a9933f4618cfe6ec8d18e2e8f91816e5ddbba"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "cpe": "cpe:2.3:a:canonical:lxd:*:*:*:*:*:*:*:*",
                    "range": [
                      {
                        "introduced": "4.0.0"
                      },
                      {
                        "fixed": "4.0.12"
                      }
                    ],
                    "source": "CPE_RANGE"
                  },
                  {
                    "cpe": "cpe:2.3:a:canonical:lxd:*:*:*:*:*:*:*:*",
                    "range": [
                      {
                        "introduced": "5.0.0"
                      },
                      {
                        "fixed": "5.0.4"
                      }
                    ],
                    "source": "CPE_RANGE"
                  },
                  {
                    "cpe": "cpe:2.3:a:canonical:lxd:*:*:*:*:*:*:*:*",
                    "range": [
                      {
                        "introduced": "5.1"
                      },
                      {
                        "fixed": "5.21.2"
                      }
                    ],
                    "source": "CPE_RANGE"
                  }
                ]
              }
            }
          ],
          "versions": [
            "show",
            "lxd-4.0.11",
            "lxd-4.0.9",
            "lxd-5.17",
            "lxd-5.16",
            "lxd-5.15",
            "lxd-5.14",
            "lxd-5.13",
            "lxd-5.12",
            "lxd-5.11",
            "lxd-5.0.2",
            "lxd-5.10",
            "lxd-5.9",
            "lxd-5.8",
            "lxd-5.7",
            "lxd-5.6",
            "lxd-5.5",
            "lxd-5.0.1",
            "lxd-5.4",
            "lxd-5.3",
            "lxd-5.2",
            "lxd-5.1",
            "lxd-5.0.0",
            "lxd-4.0.8",
            "lxd-4.0.7",
            "lxd-4.0.6",
            "lxd-4.0.5",
            "lxd-4.0.4",
            "lxd-4.0.3",
            "lxd-4.0.2",
            "lxd-4.0.1",
            "lxd-4.0.0"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-66898.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:37.414197439Z",
      "provider": "osv",
      "references": [
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/66xxx/CVE-2026-66898.json",
        "https://github.com/canonical/lxd/security/advisories/GHSA-m857-c7gc-c984",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-66898",
        "https://github.com/canonical/lxd"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-22"
        ],
        "cna_assigner": "canonical",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/66xxx/CVE-2026-66898.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-66898",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 504888,
  "published_at": "2026-08-12T20:07:32.889+00:00"
}