CVE-2023-37271

RestrictedPython is a tool that helps to define a subset of the Python
language which allows users to provide a program input into a trusted
environment. RestrictedPython does not check access to stack frames and
their attributes. Stack frames are accessible within at least generators
and generator expressions, which are allowed inside RestrictedPython. Prior
to versions 6.1 and 5.3, an attacker with access to a RestrictedPython
environment can write code that gets the current stack frame in a generator
and then walk the stack all the way beyond the RestrictedPython invocation
boundary, thus breaking out of the restricted sandbox and potentially
allowing arbitrary code execution in the Python interpreter. All
RestrictedPython deployments that allow untrusted users to write Python
code in the RestrictedPython environment are at risk. In terms of Zope and
Plone, this would mean deployments where the administrator allows untrusted
users to create and/or edit objects of type Script (Python), DTML Method, DTML Document or Zope Page Template. This is a non-default
configuration and likely to be extremely rare. The problem has been fixed
in versions 6.1 and 5.3.