CVE-2026-104851
HIGHDescription
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.
How to fix
TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works
Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.
CVSS v3 Vector
Exploitability
Impact
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Exploit Intelligence
Low risk: more likely to be exploited than 23% of all known CVEs.
References
Related Vulnerabilities
Other CWE-94 (Code Injection) vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2017-9841 | Critical | 9.8 | 100% | KEV | Fix |
| CVE-2015-1635 | Critical | 9.8 | 100% | KEV | - |
| CVE-2022-22954 | Critical | 9.8 | 100% | KEV + Ransom | - |
| CVE-2025-49704 | High | 8.8 | 100% | KEV + Ransom | Fix |
| CVE-2025-3248 | Critical | 9.8 | 100% | KEV + Ransom | Fix |
| CVE-2021-22204 | Medium | 6.8 | 100% | KEV | Fix |
Common questions
How do I fix CVE-2026-104851?
Upgrade fsspec on debian unstable to 2026.9.0-1 or later.
Is CVE-2026-104851 being actively exploited?
Not that we know of. CVE-2026-104851 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.32% is the estimated probability that it will be exploited in the next 30 days. That is higher than 23% of all scored CVEs.
How severe is CVE-2026-104851?
CVE-2026-104851 has a CVSS v3 base score of 8.8, rated high. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.
What does CVE-2026-104851 affect?
Published advisories record a fix for fsspec (Debian). Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.
Embed a live status badge for CVE-2026-104851
Markdown
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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-10-05.