fontTools is Vulnerable to Arbitrary File Write and XML injection in fontTools.varLib

{
  "id": "5d449e180088b942bbb467685d64d58e3595d6d1a11636772299b2fefd607df8",
  "url": "https://osv.dev/vulnerability/CVE-2025-66034",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "fontTools is Vulnerable to Arbitrary File Write and XML injection in fontTools.varLib",
    "summary": "fontTools is a library for manipulating fonts, written in Python. In versions from 4.33.0 to before 4.60.2, the fonttools varLib (or python3 -m fontTools.varLib) script has an arbitrary file write vulnerability that leads to remote code execution when a malicious .designspace file is processed. The vulnerability affects the main() code path of fontTools.varLib, used by the fonttools varLib CLI and any code that invokes fontTools.varLib.main(). This issue has been patched in version 4.60.2.",
    "evidence": "osv:CVE-2025-66034",
    "products": [],
    "severity": "medium",
    "structured": {
      "id": "CVE-2025-66034",
      "aliases": [
        "CVE-2025-66034",
        "GHSA-768j-98cg-p3fv",
        "PYSEC-2026-1389"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:C/C:N/I:H/A:L"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/fonttools/fonttools",
              "type": "GIT",
              "events": [
                {
                  "introduced": "f81ec49a666fbb35ea0af975d80d6a6a06ccc43a"
                },
                {
                  "fixed": "78ba5e8bb4ccf65ef8077d81bc48450ccacf1728"
                },
                {
                  "fixed": "a696d5ba93270d5954f98e7cab5ddca8a02c1e32"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "cpe": "cpe:2.3:a:fonttools:fonttools:*:*:*:*:*:python:*:*",
                    "range": [
                      {
                        "introduced": "4.33.0"
                      },
                      {
                        "fixed": "4.60.2"
                      }
                    ],
                    "source": "CPE_RANGE"
                  },
                  {
                    "range": [
                      {
                        "fixed": "a696d5ba93270d5954f98e7cab5ddca8a02c1e32"
                      }
                    ],
                    "source": "REFERENCES_COMMIT"
                  }
                ]
              }
            }
          ],
          "versions": [
            "4.61.0",
            "4.60.1",
            "4.60.0",
            "4.59.2",
            "4.59.1",
            "4.59.0",
            "4.58.5",
            "4.58.4",
            "4.58.3",
            "4.58.2",
            "4.58.1",
            "4.58.0",
            "4.57.0",
            "4.56.0",
            "4.55.8",
            "4.55.7",
            "4.55.6",
            "4.55.5",
            "4.55.4",
            "4.55.3",
            "4.55.2",
            "4.55.0",
            "4.54.1",
            "4.54.0",
            "4.53.1",
            "4.53.0",
            "4.52.4",
            "4.52.3",
            "4.52.2",
            "4.52.1",
            "4.52.0",
            "4.51.0",
            "4.50.0",
            "4.49.0",
            "4.48.1",
            "4.48.0",
            "4.47.2",
            "4.47.1",
            "4.47.0",
            "4.46.0",
            "4.45.1",
            "4.45.0",
            "4.44.3",
            "4.44.2",
            "4.44.1",
            "4.44.0",
            "4.43.1",
            "4.43.0",
            "4.42.1",
            "4.42.0",
            "4.41.1",
            "4.41.0",
            "4.40.0",
            "4.39.4",
            "4.39.3",
            "4.39.2",
            "4.39.1",
            "4.39.0",
            "4.38.0",
            "4.37.4",
            "4.37.3",
            "4.37.2",
            "4.37.1",
            "4.37.0",
            "4.36.0",
            "4.35.0",
            "4.34.4",
            "4.34.3",
            "4.34.2",
            "4.34.1",
            "4.34.0",
            "4.33.3",
            "4.33.1",
            "4.33.0"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2025-66034.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:49.999434654Z",
      "provider": "osv",
      "references": [
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/66xxx/CVE-2025-66034.json",
        "https://github.com/fonttools/fonttools/security/advisories/GHSA-768j-98cg-p3fv",
        "https://nvd.nist.gov/vuln/detail/CVE-2025-66034",
        "https://github.com/fonttools/fonttools/commit/a696d5ba93270d5954f98e7cab5ddca8a02c1e32"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-91"
        ],
        "cna_assigner": "GitHub_M",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/66xxx/CVE-2025-66034.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2025-66034",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 518559,
  "published_at": "2025-11-29T01:07:12.193+00:00"
}