CVE-2023-41039: RestrictedPython is a restricted execution environment for Python to run untrusted code

This month

HIGH 8.3UPGRADE

CVE-2023-41039 is a high-severity flaw (CVSS 8.3) affecting restrictedpython. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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 `u

Why this priority

High severity

A fixed release or distro patch exists.

Risk facts

CVSS score	8.3 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	High
User interaction	Required
EPSS exploit chance	0.7% (top 48%)
CISA exploited list	No
Weakness	CWE-74
Published	2023-08-30
Last modified	2026-06-17

Publisher (CNA): GitHub, Inc. · Vendor: zope

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2023-08-30 18:15 UTCPublished CVE record published
2026-06-17 06:20 UTCUpdated Record last modified

zope restrictedpython UPGRADE

Affected: < 5.4 · >= 6.0 and < 6.2

Fixed in: 5.4, 6.2

Safe to downgrade to: a release before 6.0

1. Check installed version

apt-cache policy restrictedpython || rpm -q restrictedpython || restrictedpython --version

2. UPGRADE to 5.4 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade restrictedpython

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade restrictedpython

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 6.0 (Debian / Ubuntu)

apt-cache madison restrictedpython sudo apt install restrictedpython=<VERSION_BEFORE_6.0> sudo apt-mark hold restrictedpython

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list restrictedpython sudo dnf downgrade restrictedpython-<VERSION_BEFORE_6.0> sudo dnf versionlock add restrictedpython

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2023-41039?

restrictedpython: upgrade to 5.4, 6.2. Exact commands for each OS are on this page.

Is CVE-2023-41039 being exploited?

CVE-2023-41039 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2023-41039 affect?

CVE-2023-41039 affects restrictedpython. Severity is high (CVSS 8.3). 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 su

How urgent is CVE-2023-41039?

Priority 42/100. High severity

Software pages

Python vulnerabilities

Related CVEs

CVE-2024-47532 MEDIUM 6.5 UPGRADE RestrictedPython is a restricted execution environment for Python to run untrusted code
CVE-2023-37271 HIGH 8.4 UPGRADE RestrictedPython is a tool that helps to define a subset of the Python language which allows users to provide

References

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