How severe is CVE-2021-32811?

CVE-2021-32811 has a CVSS score of 7.2/10, rated HIGH. Immediate patching is strongly recommended.

Which packages are affected by CVE-2021-32811?

CVE-2021-32811 affects the following packages: zope (PyPI), zope (PyPI). Ecosystems affected: PyPI.

How do I fix CVE-2021-32811?

Update zope to 4.6.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-32811 is resolved across your whole dependency graph.

How do I detect CVE-2021-32811 in my PyPI dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for zope, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2021-32811 if there is no patch (or I can't update yet)?

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Is CVE-2021-32811 actively exploited in the wild?

No public exploit code has been indexed for CVE-2021-32811 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2021-32811?

CVE-2021-32811 has an EPSS (Exploit Prediction Scoring System) score of 2.3%, placing it in the 83th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2021-32811?

CVE-2021-32811 is classified as CWE-915 (CWE-915), CWE-1321 (CWE-1321). These weakness types describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2021-32811 published, and has it been updated?

CVE-2021-32811 was published on August 2, 2021 and was last updated on July 9, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐍

🐍 PyPI

Not in CISA KEV

HIGH severity

CVE-2021-32811 — zope

HIGHFix: zopefoundation/Zope@f72a18d

CVE-2021-32811 is a high-severity (CVSS 7.2) CWE-915 vulnerability in zope. A fix is available for zope — see the affected versions and patch details below.

Remote Code Execution via Script (Python) objects under Python 3

Also known asGHSA-g4gq-j4p2-j8frPYSEC-2021-368PYSEC-2021-370

Published

Aug 2, 2021

Updated

Jul 9, 2026

Affected

2 pkgs

Patched

2 / 2

Exploits

None indexed

Exploitation data as of Oct 8, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗

2.3%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs83th percentile — riskier than 83% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

CVE-2021-32811 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 385,738 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.

Real-World Exposure

2 pkgs affected

🐍zope🐍zope

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.

Description

Impact

Background: The optional add-on package Products.PythonScripts adds Script (Python) to the list of content items a user can add to the Zope object database. Inside these scripts users can write Python code that is executed when rendered through the web. The code environment in these script objects is limited, it relies on the RestrictedPython package to provide a "safe" subset of Python instructions as well as the AccessControl package that defines security policies for execution in the context of a Zope application.

Recently the AccessControl package was updated to fix a remote code execution security issue. A link to the security advisory is provided in the References section below. The bug tightens the AccessControl security policies for Zope by blocking access to unsafe classes inside the Python string module.

You are only affected if the following are true:

You use Python 3 for your Zope deployment (Zope 4 on Python 2 is not affected)
You run Zope 4 below version 4.6.3 or Zope 5 below version 5.3
You have installed the optional Products.PythonScripts add-on package

By default, you need to have the admin-level Zope "Manager" role to add or edit Script (Python) objects through the web. Only sites that allow untrusted users to add/edit these scripts through the web - which would be a very unusual configuration to begin with - are at risk.

Patches

The problem has been fixed in AccessControl versions 4.3 and 5.2. Zope releases 4.6.3 and 5.3 now require these new AccessControl releases.

Workarounds

A site administrator can restrict adding/editing Script (Python) objects through the web using the standard Zope user/role permission mechanisms. Untrusted users should not be assigned the Zope Manager role and adding/editing these scripts through the web should be restricted to trusted users only. This is the default configuration in Zope.

References

AccessControl security advisory GHSA-qcx9-j53g-ccgf

For more information

If you have any questions or comments about this advisory:

Open an issue in the Zope issue tracker
Email us at [email protected]

Affected Packages

2 total 2 fixed

Ecosystem	Package	Vulnerable range	Fix
🐍PyPI	`zope`	≥ 4.0&&< 4.6.3	4.6.3`pip install --upgrade 'zope==4.6.3'`
🐍PyPI	`zope`	≥ 5.0&&< 5.3	5.3`pip install --upgrade 'zope==5.3'`

Affected Products

2 products · 4 configurations

Application

accesscontrolzope

≥ 5.0 && < 5.2

range

Application

zopezope

≥ 5.0 && < 5.3

range

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for zope, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update zope to 4.6.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-32811 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Frequently Asked Questions

### Impact Background: The optional add-on package `Products.PythonScripts` adds `Script (Python)` to the list of content items a user can add to the Zope object database. Inside these scripts users can write Python code that is executed when rendered through the web. The code environment in these script objects is limited, it relies on the `RestrictedPython` package to provide a "safe" subset of Python instructions as well as the `AccessControl` package that defines security policies for execution in the context of a Zope application. Recently the `AccessControl` package was updated to fix a