CVE-2023-37271: RestrictedPython vulnerable to arbitrary code execution via stack frame sandbox escape

Vulnerability summary

CVE-2023-37271 is a critical (CVSS 9.9) vulnerability in zope restrictedpython. EPSS estimates a 0.85% chance of exploitation in the next 30 days, higher than 58.1% of scored vulnerabilities.

Timeline

1. 11-07-2023
   PublishedVulnerability first disclosed.
2. 07-11-2024
   Last modifiedVulnerability information updated.

Description

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.

• CWE-913Improper Control of Dynamically-Managed Code ResourcesThe product does not properly restrict reading from or writing to dynamically-managed code resources such as variables, objects, classes, attributes, functions, or executable instructions or statements.