PYSEC-2026-4217 fsspec: Server-Side Template Injection in ReferenceFileSystem leads to Remote Code Execution

Summary fsspec.implementations.reference.ReferenceFileSystem parses a "references" JSON document Kerchunk format supplied either inline or via a URL. The parser renders fields from this JSON through un-sandboxed jinja2.Template....render... calls in three locations. An attacker who controls the...

fsspec: Server-Side Template Injection in ReferenceFileSystem leads to Remote Code Execution

Summaryfsspec.implementations.reference.ReferenceFileSystem parses a "references"JSON document Kerchunk format supplied either inline or via a URL. Theparser renders fields from this JSON through un-sandboxedjinja2.Template....render... calls in three locations. An attacker whocontrols the JSON...

GHSA-27VJ-QCQG-25RC fsspec: Server-Side Template Injection in ReferenceFileSystem leads to Remote Code Execution

Summary fsspec.implementations.reference.ReferenceFileSystem parses a "references" JSON document Kerchunk format supplied either inline or via a URL. The parser renders fields from this JSON through un-sandboxed jinja2.Template....render... calls in three locations. An attacker who controls the...

fsspec: Server-Side Template Injection in ReferenceFileSystem leads to Remote Code Execution

Summary fsspec.implementations.reference.ReferenceFileSystem parses a "references" JSON document Kerchunk format supplied either inline or via a URL. The parser renders fields from this JSON through un-sandboxed jinja2.Template....render... calls in three locations. An attacker who controls the...

CVE-2026-104851

A flaw was found in fsspec. This vulnerability can lead to arbitrary code execution due to unrestricted template evaluation in the ReferenceFileSystem component. When processing filesystem reference metadata documents, template expressions are evaluated without security restrictions or sandboxing...

Arbitrary Code Injection

Overview fsspec is a File-system specification Affected versions of this package are vulnerable to Arbitrary Code Injection in the reference filesystem process. An attacker can execute arbitrary code by tricking an application into loading a maliciously crafted reference document, such as a...