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 environme...

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.

Metrics

CVSS 3.1

9.9/10

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

EPSS Probability

0.77%

50.9th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-913

Affected Software

Vendor	Product	Versions
Zope	Restrictedpython	< 5.3
Zope	Restrictedpython	6.0

References

Timeline

Published: Jul 11, 2023
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is 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.

How severe is CVE-2023-37271?

CVE-2023-37271 has a CVSS score of 9.9/10 (CRITICAL severity). The EPSS model estimates a 0.77% probability of exploitation in the next 30 days.

How do I fix CVE-2023-37271?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.