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CVE-2026-104851— fsspec: Server-Side Template Injection in ReferenceFileSystem leads to Remote Code Execution

Quick assessment

Affected
fsspec filesystem_spec
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

fsspec 是一套用于文件系统接口的规范及 Python 实现框架。在 0.9.0 至 2026.6.0 版本期间，fsspec.implementations.reference.ReferenceFileSystem 通过无限制的 jinja2.Template(...).render(...) 调用来评估来自 Kerchunk 参考 JSON 文档中的字段。这些调用发生在 fsspec/implementations/reference.py 文件中的 _process_references1._rende

CVSS 8.8 · High EPSS 0.32% · P22

Affected Version Matrix 1

VendorProduct Version RangeStatus
fsspec filesystem_spec >= 0.9.0, < 2026.6.0 affected
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I. Basic Information for CVE-2026-104851

Vulnerability Information
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Vulnerability Title
fsspec: Server-Side Template Injection in ReferenceFileSystem leads to Remote Code Execution
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
对生成代码的控制不恰当(代码注入)
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
fsspec filesystem_spec >= 0.9.0, < 2026.6.0 -

II. Public POCs for CVE-2026-104851

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III. Intelligence Information for CVE-2026-104851

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Patches & Fixes for CVE-2026-104851 (2)

Vendor Advisories for CVE-2026-104851 (1)

Vendor Pages for CVE-2026-104851 (1)

IV. Related Vulnerabilities

Same weakness: CWE-94

V. Comments for CVE-2026-104851

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