high
7.2
CWE
1321 915
Advisory Published
Advisory Published
Updated

CVE-2021-32807: Remote Code Execution via unsafe classes in otherwise permitted modules

First published: Fri Jul 30 2021(Updated: )

### Impact The module `AccessControl` defines security policies for Python code used in restricted code within Zope applications. Restricted code is any code that resides in Zope's object database, such as the contents of `Script (Python)` objects. The policies defined in `AccessControl` severely restrict access to Python modules and only exempt a few that are deemed safe, such as Python's `string` module. However, full access to the `string` module also allows access to the class `Formatter`, which can be overridden and extended within `Script (Python)` in a way that provides access to other unsafe Python libraries. Those unsafe Python libraries can be used for remote code execution. By default, you need to have the admin-level Zope "Manager" role to add or edit `Script (Python)` objects through the web. Only sites that allow untrusted users to add/edit these scripts through the web - which would be a very unusual configuration to begin with - are at risk. ### Patches The problem has been fixed in AccessControl 4.3 and 5.2. Only AccessControl versions 4 and 5 are vulnerable, and only on Python 3, not Python 2.7. ### Workarounds A site administrator can restrict adding/editing `Script (Python)` objects through the web using the standard Zope user/role permission mechanisms. Untrusted users should not be assigned the Zope Manager role and adding/editing these scripts through the web should be restricted to trusted users only. This is the default configuration in Zope. ### For more information If you have any questions or comments about this advisory: * Open an issue in the [AccessControl issue tracker](https://github.com/zopefoundation/AccessControl/issues) * Email us at [security@plone.org](mailto:security@plone.org)

Credit: security-advisories@github.com security-advisories@github.com

Affected SoftwareAffected VersionHow to fix
Zope Accesscontrol>=4.0<4.3
Zope Accesscontrol>=5.0<5.2
pip/AccessControl>=5.0<5.2
5.2
pip/AccessControl>=4.0<4.3
4.3
>=4.0<4.3
>=5.0<5.2

Remedy

https://github.com/zopefoundation/AccessControl/commit/b42dd4badf803bb9fb71ac34cd9cb0c249262f2c

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Reference Links

Frequently Asked Questions

  • What is CVE-2021-32807?

    CVE-2021-32807 is a vulnerability in the Zope AccessControl module that allows unrestricted access to restricted code within Zope applications.

  • What is the severity of CVE-2021-32807?

    CVE-2021-32807 has a severity score of 7.2, which is considered high.

  • How does CVE-2021-32807 affect Zope AccessControl?

    CVE-2021-32807 affects Zope AccessControl versions 4.0 to 4.3 and versions 5.0 to 5.2.

  • How can I fix CVE-2021-32807?

    To fix CVE-2021-32807, it is recommended to update to a patched version of Zope AccessControl.

  • Where can I find more information about CVE-2021-32807?

    You can find more information about CVE-2021-32807 in the Zope AccessControl documentation and the provided references.

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