CVE-2023-41039: Sandbox escape via various forms of "format" in RestrictedPython

Vulnerability summary

CVE-2023-41039 is a high (CVSS 8.3) vulnerability in zope restrictedpython. EPSS estimates a 0.68% chance of exploitation in the next 30 days, higher than 52.5% of scored vulnerabilities.

Timeline

1. 30-08-2023
   PublishedVulnerability first disclosed.
2. 01-10-2024
   Last modifiedVulnerability information updated.

Description

RestrictedPython is a restricted execution environment for Python to run untrusted code. Python's "format" functionality allows someone controlling the format string to "read" all objects accessible through recursive attribute lookup and subscription from objects he can access. This can lead to critical information disclosure. With `RestrictedPython`, the format functionality is available via the `format` and `format_map` methods of `str` (and `unicode`) (accessed either via the class or its instances) and via `string.Formatter`. All known versions of `RestrictedPython` are vulnerable. This issue has been addressed in commit `4134aedcff1` which has been included in the 5.4 and 6.2 releases. Users are advised to upgrade. There are no known workarounds for this vulnerability.

• CWE-74Improper Neutralization of Special Elements in Output Used by a Downstream ComponentThe product constructs all or part of a command, data structure, or record using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify how it is parsed or interpreted when it is sent to a downstream component.