TI-2023-21665 Aliases CVE-2023-41039 GHSA-xjw2-6jm9-rf67

Sandbox escape via various forms of "format" in RestrictedPython

LOW 39CWE-74Published 2023-08-30 · Updated 2024-10-01

Key facts

Attack vector: Network
Privileges required: High
User interaction: Required
Attack complexity: Low
Impact type: —
Confidentiality · integrity · availability: High · High · Low
Fix status: Fixed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA and GitHub.

Summary

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.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV

EPSS 0.00683 52nd percentileScored 2026-11-07

Fix Fixed RestrictedPython (zopefoundation): 5.4, 6.1RestrictedPython (PyPI): 5.4, 6.2

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation: None
Automatable: No
Technical impact: Total

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

Vendor	Product	Affected versions	Fixed in	Status	Source
zopefoundation	RestrictedPython	before 5.4; 6.0 to before 6.1	5.4, 6.1	Patch available	CNA
—	RestrictedPython (PyPI)	before 5.4	5.4	Patch available	GHSA-xjw2-6jm9-rf67
—	RestrictedPython (PyPI)	6.0 to before 6.2	6.2	Patch available	GHSA-xjw2-6jm9-rf67

RestrictedPython Vendorzopefoundation Affected before 5.4; 6.0 to before 6.1 Fixed in 5.4, 6.1 Patch available CNA
RestrictedPython (PyPI) Vendor— Affected before 5.4 Fixed in 5.4 Patch available GHSA-xjw2-6jm9-rf67
RestrictedPython (PyPI) Vendor— Affected 6.0 to before 6.2 Fixed in 6.2 Patch available GHSA-xjw2-6jm9-rf67

CPE configurations NVD · 1

CPE	Versions	Role	Vendor
cpe:2.3:a:zope:restrictedpython::::::::	before 5.4; 6.0 to before 6.2	Vulnerable	zopefoundation

cpe:2.3:a:zope:restrictedpython:*:*:*:*:*:*:*:* Versions before 5.4; 6.0 to before 6.2 Vulnerable ·zopefoundation

Remediation

Fix · CNA RestrictedPython (zopefoundation) Fixed in 5.4, 6.1
Fix · GHSA-xjw2-6jm9-rf67 RestrictedPython (PyPI) Fixed in 5.4 Advisory →
Fix · GHSA-xjw2-6jm9-rf67 RestrictedPython (PyPI) Fixed in 6.2 Advisory →

Timeline

2026-10-02 Threatist record created from CVE-2023-41039
2026-10-03 Alias added: GHSA-xjw2-6jm9-rf67

References

Patch 1

https://github.com/zopefoundation/RestrictedPython/commit/4134aedcff17c977da7717693ed89ce56d54c120

Advisory 2

Other 1

https://github.com/zopefoundation/RestrictedPython

TI-2024-31821 RestrictedPython information leakage via `AttributeError.obj` and the `string` module CVSS 4.0HIGH 8.7
TI-2023-18901 RestrictedPython vulnerable to arbitrary code execution via stack frame sandbox escape CVSS 3.1CRITICAL 9.9

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences