{"id":"DEBIAN-CVE-2026-104851","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.","modified":"2026-10-03T05:00:12.621101507Z","published":"2026-10-02T17:17:03.763Z","upstream":["CVE-2026-104851"],"references":[{"type":"ADVISORY","url":"https://security-tracker.debian.org/tracker/CVE-2026-104851"}],"affected":[{"package":{"name":"fsspec","ecosystem":"Debian:12","purl":"pkg:deb/debian/fsspec?arch=source&distro=bookworm"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2022.11.0-1","2023.10.0-1","2023.3.0-1~exp1","2023.6.0-1","2023.9.2-1","2024.10.0-1","2024.12.0-1","2024.12.0-2","2024.2.0-1","2024.3.1-1","2024.5.0-1","2024.6.0-1","2024.6.1-1","2024.9.0-1","2025.12.0-1","2025.2.0-1","2025.3.0-1","2025.3.2-1","2025.7.0-1","2025.7.0-2","2025.7.0-3","2025.7.0-4"],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-104851.json"}},{"package":{"name":"fsspec","ecosystem":"Debian:13","purl":"pkg:deb/debian/fsspec?arch=source&distro=trixie"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2025.12.0-1","2025.3.2-1","2025.7.0-1","2025.7.0-2","2025.7.0-3","2025.7.0-4"],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-104851.json"}},{"package":{"name":"fsspec","ecosystem":"Debian:14","purl":"pkg:deb/debian/fsspec?arch=source&distro=forky"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2025.12.0-1","2025.3.2-1","2025.7.0-1","2025.7.0-2","2025.7.0-3","2025.7.0-4"],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-104851.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H"}]}