| Package | Affected versions | Patched versions |
|---|---|---|
| restrictedpython | ≥ 6.0a1.dev0, < 6.1< 5.3 | 6.15.3 |
| restrictedpython | = 6.0< 5.3 | 5.3 |
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. 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 scope allowing the call of unrestricted Python code and therefore 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 releases 5.3 and 6.1.
There is no workaround available. If you cannot upgrade to the latest release you should ensure the RestrictedPython environment is only available for trusted users.
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