python / python/cpython

docs: Zipfile contains a 13-years outdated warning regarding path sanitization

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Descripción

Documentation

The extract/extractall documentation contains a warning that became outdated 13 years ago:

https://docs.python.org/3/library/zipfile.html#zipfile.ZipFile.extractall

"Warning: Never extract archives from untrusted sources without prior inspection. It is possible that files are created outside of path, for example, members that have absolute filenames or filenames with “..” components. This module attempts to prevent that. See extract() note."

This incorrect and completely outdated comment should have been deleted when the malicious zip sanitization was added to Python 13 years ago, in February 2013:

https://github.com/python/cpython/commit/b47acbf46abd425f69dcc03e9b4f0c7f7c321ac2

Here's the official Python code:

https://github.com/python/cpython/blob/main/Lib/zipfile/__init__.py#L2467

Both extract() and extractall() use _extract_member, which performs complete sanitizing:

# 1. Strips leading slashes (/), drive letters (C:), and UNC paths (\\server\share)
drive, root, arcname = os.path.splitroot(arcname)
...
# 2. Defines invalid parts: empty strings, current directory (.), and parent directory (..)
invalid_path_parts = ('', os.path.curdir, os.path.pardir)

# 3. Filters out any occurrences of '.' and '..'
arcname = os.path.sep.join(x for x in arcname.split(os.path.sep)
                           if x not in invalid_path_parts)

And even the original Zip Slip author said that Python is not vulnerable:

https://security.snyk.io/research/zip-slip-vulnerability

"We also vetted the Ruby and Python ecosystems and couldn’t find any vulnerable code snippets or libraries. In fact, Python libraries were vulnerable until fixed in 2014. Ruby has a number of existing vulnerabilities that have been fixed in previous versions here , here and here."

(He's wrong about 2014; Python added the malicious Zip path sanitization in February 2013.)

Guía de contribución

Abrir la guía de contribución

Primeros pasos

  1. Lee el issue completo y luego la guía de contribución del proyecto.
  2. Comenta en el issue que vas a ocuparte — evita que dos personas hagan lo mismo.
  3. Haz un fork del repositorio y trabaja en una rama.
  4. Abre un pull request que haga referencia al número del issue.

Línea de trabajo

Comienza con la documentación de ZipFile.extractall enlazada en el issue y revisa la implementación relacionada de _extract_member en Lib/zipfile/init.py. Elimina la advertencia obsoleta sobre la sanitización de rutas y, a continuación, genera o valida la documentación para confirmar que las referencias a extract() y extractall() siguen siendo correctas.

Escrito por el modelo de indexación a partir del texto del issue.

Evaluación

Stack tecnológico
python
Área
documentation
Tipo de issue
Documentación
Dificultad
2/5
Tiempo estimado
1-3 horas
Estado de actividad
Activo
Claridad
Bien especificado
Aptitud para principiantes
78/100

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