{"id":"CVE-2026-104851","published":"2026-10-02T17:17:03.763","lastModified":"2026-10-05T20:17:09.373","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.","cvssScore":8.8,"cvssSeverity":"HIGH","cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H","cwes":["CWE-94","CWE-1336"],"vendors":[],"products":[],"references":[{"url":"https://github.com/fsspec/filesystem_spec/commit/86438783f93b1398ef245b92f0e6063b445b611c","tags":[]},{"url":"https://github.com/fsspec/filesystem_spec/commit/a1c16ab3f07f354aa371c38f7b1b07ea7fd4c5c8","tags":[]},{"url":"https://github.com/fsspec/filesystem_spec/pull/2029","tags":[]},{"url":"https://github.com/fsspec/filesystem_spec/pull/2039","tags":[]},{"url":"https://github.com/fsspec/filesystem_spec/releases/tag/2026.6.0","tags":[]},{"url":"https://github.com/fsspec/filesystem_spec/security/advisories/GHSA-27vj-qcqg-25rc","tags":[]},{"url":"https://github.com/fsspec/filesystem_spec/security/advisories/GHSA-27vj-qcqg-25rc","tags":[]}],"exploitRefs":[{"url":"https://github.com/fsspec/filesystem_spec/commit/86438783f93b1398ef245b92f0e6063b445b611c","tags":[]},{"url":"https://github.com/fsspec/filesystem_spec/commit/a1c16ab3f07f354aa371c38f7b1b07ea7fd4c5c8","tags":[]},{"url":"https://github.com/fsspec/filesystem_spec/pull/2029","tags":[]},{"url":"https://github.com/fsspec/filesystem_spec/pull/2039","tags":[]},{"url":"https://github.com/fsspec/filesystem_spec/releases/tag/2026.6.0","tags":[]},{"url":"https://github.com/fsspec/filesystem_spec/security/advisories/GHSA-27vj-qcqg-25rc","tags":[]},{"url":"https://github.com/fsspec/filesystem_spec/security/advisories/GHSA-27vj-qcqg-25rc","tags":[]}],"hasPoc":true,"ai":{"summary":"The flaw allows attackers to execute arbitrary Python code by manipulating template expressions in Kerchunk reference JSON documents, posing a high risk due to the potential for remote code execution.","exploitability":"Exploitation is moderately hard as it requires attackers to control the template expressions in the JSON documents, but preconditions include the use of the reference filesystem and the presence of template-related options and values.","blast_radius":"If exploited, the impact could be severe, as it allows execution of arbitrary code, potentially leading to full system compromise or data loss.","remediation":"Upgrade to version 2026.6.0 or later.","detection":"No reliable host or network indicator is derivable from the published description.","tags":["rce","python","template","json","filesystem"],"model":"qwen2.5:7b-instruct","analyzedAt":"2026-10-03T08:54:10.189Z"}}