2021-32807 | Zope AccessControl dynamically-determined object attributes
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A vulnerability, which was classified as problematic, was found in Zope AccessControl up to 4.2/5.1 (Application Server Software). CWE is classifying the issue as CWE-915. This is going to have an impact on confidentiality, integrity, and availability. The summary by CVE is:
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. 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. As a workaround, 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.
The weakness was disclosed 07/31/2021. It is possible to read the advisory at github.com. This vulnerability is uniquely identified as CVE-2021-32807 since 05/12/2021. The exploitability is told to be difficult. It is possible to initiate the attack remotely. Additional levels of successful authentication are required for exploitation. The technical details are unknown and an exploit is not publicly available.
Upgrading to version 4.3 or 5.2 eliminates this vulnerability. The upgrade is hosted for download at github.com. Applying a patch is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version.
VulDB Meta Base Score: 4.1
VulDB Meta Temp Score: 3.9
Status: Not defined
0-Day Time: 🔒
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