{
  "affected": [
    {
      "ranges": [
        {
          "database_specific": {
            "extracted_events": [
              {
                "introduced": "0.9.0"
              },
              {
                "fixed": "2026.6.0"
              }
            ],
            "source": [
              "AFFECTED_FIELD",
              "REFERENCES"
            ]
          },
          "events": [
            {
              "introduced": "c7d996685de74d2e3dc7f68b3c4722842a6914bc"
            },
            {
              "fixed": "86438783f93b1398ef245b92f0e6063b445b611c"
            },
            {
              "fixed": "a1c16ab3f07f354aa371c38f7b1b07ea7fd4c5c8"
            },
            {
              "fixed": "a2457004d03e0312f715f90f58873de5ab195a37"
            }
          ],
          "repo": "https://github.com/fsspec/filesystem_spec",
          "type": "GIT"
        }
      ]
    }
  ],
  "aliases": [
    "GHSA-27vj-qcqg-25rc"
  ],
  "database_specific": {
    "cna_assigner": "GitHub_M",
    "cwe_ids": [
      "CWE-1336",
      "CWE-94"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/104xxx/CVE-2026-104851.json"
  },
  "details": "fsspec is a specification and Python implementation framework for filesystem interfaces. From 0.9.0 until 2026.6.0, fsspec.implementations.reference.ReferenceFileSystem evaluates fields from Kerchunk reference JSON documents through unrestricted jinja2.Template(...).render(...) calls in _process_references1._render_jinja, _process_templates, and _process_gen in fsspec/implementations/reference.py. A document supplied inline or fetched from an attacker-controlled URL can provide template expressions that execute Python code when the reference filesystem is opened, including through consumers such as xarray, before referenced data is read. The _process_gen path is reached whenever a document includes a gen array, while the other paths depend on template-related options and values. This issue is fixed in version 2026.6.0.",
  "id": "CVE-2026-104851",
  "modified": "2026-10-07T02:30:38.709205277Z",
  "published": "2026-10-02T16:36:48.513Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/fsspec/filesystem_spec/releases/tag/2026.6.0"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/104xxx/CVE-2026-104851.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/fsspec/filesystem_spec/security/advisories/GHSA-27vj-qcqg-25rc"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-104851"
    },
    {
      "type": "FIX",
      "url": "https://github.com/fsspec/filesystem_spec/commit/86438783f93b1398ef245b92f0e6063b445b611c"
    },
    {
      "type": "FIX",
      "url": "https://github.com/fsspec/filesystem_spec/commit/a1c16ab3f07f354aa371c38f7b1b07ea7fd4c5c8"
    },
    {
      "type": "FIX",
      "url": "https://github.com/fsspec/filesystem_spec/pull/2029"
    },
    {
      "type": "FIX",
      "url": "https://github.com/fsspec/filesystem_spec/pull/2039"
    }
  ],
  "schema_version": "1.9.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "fsspec: Server-Side Template Injection in ReferenceFileSystem leads to Remote Code Execution"
}