{"cve":"CVE-2026-104851","nvd":{"published":"2026-10-02T17:17:03.763","modified":"2026-10-05T20:17:09.373","status":"Deferred","description":"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.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H","score":8.8},"cwes":["CWE-94","CWE-1336"],"references":["https://github.com/fsspec/filesystem_spec/commit/86438783f93b1398ef245b92f0e6063b445b611c","https://github.com/fsspec/filesystem_spec/commit/a1c16ab3f07f354aa371c38f7b1b07ea7fd4c5c8","https://github.com/fsspec/filesystem_spec/pull/2029","https://github.com/fsspec/filesystem_spec/pull/2039","https://github.com/fsspec/filesystem_spec/releases/tag/2026.6.0"],"products":[],"source":"nvd","synced_at":"2026-10-19T22:57:46.668721662+00:00"},"epss":{"cve":"CVE-2026-104851","score":0.00475,"percentile":0.40757,"date":"2026-10-25"},"kev":null,"osv":[{"id":"GHSA-27vj-qcqg-25rc","url":"https://osv.dev/vulnerability/GHSA-27vj-qcqg-25rc","summary":"fsspec: Server-Side Template Injection in ReferenceFileSystem leads to Remote Code Execution","modified":"2026-10-15T14:56:18.658408345Z","packages":[{"ecosystem":"PyPI","name":"fsspec","purl":"pkg:pypi/fsspec","ranges":[">=0.9.0 <2026.6.0"],"fixed":["2026.6.0"]}]},{"id":"PYSEC-2026-4217","url":"https://osv.dev/vulnerability/PYSEC-2026-4217","summary":"fsspec: Server-Side Template Injection in ReferenceFileSystem leads to Remote Code Execution","modified":"2026-10-15T14:45:07.362640573Z","packages":[{"ecosystem":"PyPI","name":"fsspec","purl":"pkg:pypi/fsspec","ranges":[">=0.9.0 <2026.6.0"],"fixed":["2026.6.0"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}