CVE-2026-104851
HighCVSS 8.8Exploitation Probability (EPSS)
Low risk23th percentile - higher than 23% of all known CVEs
Summary
fsspec from 0.9.0 to 2026.6.0 contains a vulnerability involving unrestricted Jinja2 template rendering in Kerchunk reference documents. An attacker can supply a malicious document that executes Python code when the reference filesystem is opened, including through consumers such as xarray.
Risk Assessment
The organization may be exposed to remote code execution if it processes untrusted Kerchunk reference documents, potentially leading to system compromise or data theft.
Recommendation
It is recommended to immediately upgrade fsspec to version 2026.6.0 or later and avoid opening reference documents from untrusted sources.
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Original NVD description (English source)
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.
Vulnerability data from NVD (NIST) · CISA KEV · EPSS

