Sandbox escape via various forms of "format".

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

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

EPSS

• CVE-2023-41039: 0.68% estimated exploitation activity in the next 30 days; percentile 52.56 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Impact 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 formatmap methods of str (and unicode) (accessed either via the class or its instances) and via string.Formatter. All known versions of RestrictedPython are vulnerable. Patches The issue will be fixed in 5.4 and 6.2. Workarounds There are no workarounds to fix the issue without upgrading. References https://docs.python.org/3/library/stdtypes.html#str.formatmap http://lucumr.pocoo.org/2016/12/29/careful-with-str-format/ https://www.exploit-db.com/exploits/51580 For more information If you have any questions or comments about this advisory: Open an issue in the RestrictedPython issue tracker Email us at security@plone.org Credits Thanks for analysing and reporting…

Published by the source

30 Aug 2023, 20:47 UTC

Last modified by the source

16 Feb 2024, 08:18 UTC

Source last checked

26 Oct 2026, 13:12 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-xjw2-6jm9-rf67

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-xjw2-6jm9-rf67

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# Patch Next advisory brief: CVE-2023-41039

Advisory: Sandbox escape via various forms of "format".
IDs: CVE-2023-41039, GHSA-xjw2-6jm9-rf67
Record: https://patchnext.com/advisories/cve-2023-41039 (revision 2, source checked 26 Oct 2026, 13:12 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.3)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: restrictedpython 6.2, 5.4. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI restrictedpython: affected <= 5.3; >= 6.0, <= 6.1; fixed in 5.4, 6.2

## Suggested inspection (read-only)
- `python -m pip show restrictedpython`: prints the installed version. Run with the environment that serves production active.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on restrictedpython.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-xjw2-6jm9-rf67 (OSV record GHSA-xjw2-6jm9-rf67 lists affected ranges: PyPI restrictedpython >=0 =6.0 <6.2 (fixed))
- Verified: https://github.com/advisories/GHSA-xjw2-6jm9-rf67 (GitHub-reviewed advisory GHSA-xjw2-6jm9-rf67 lists affected ranges: PyPI restrictedpython >=0 =6.0 <=6.1)

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