How severe is CVE-2021-32807?

CVE-2021-32807 has a CVSS score of 7.2/10, rated HIGH. Immediate patching is strongly recommended.

Which packages are affected by CVE-2021-32807?

CVE-2021-32807 affects the following packages: accesscontrol (PyPI), accesscontrol (PyPI), zope (PyPI), zope (PyPI). Ecosystems affected: PyPI.

How do I fix CVE-2021-32807?

Update accesscontrol to 4.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-32807 is resolved across your whole dependency graph.

How do I detect CVE-2021-32807 in my PyPI dependencies?

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

How do I mitigate CVE-2021-32807 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-2021-32807 actively exploited in the wild?

No public exploit code has been indexed for CVE-2021-32807 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-2021-32807?

CVE-2021-32807 has an EPSS (Exploit Prediction Scoring System) score of 2.0%, placing it in the 81th 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-2021-32807?

CVE-2021-32807 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-2021-32807 published, and has it been updated?

CVE-2021-32807 was published on July 30, 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-2021-32807 — accesscontrol

HIGHFix: zopefoundation/AccessControl@b42dd4b

CVE-2021-32807 is a high-severity (CVSS 7.2) CWE-915 vulnerability in accesscontrol. A fix is available for accesscontrol — see the affected versions and patch details below.

Remote Code Execution via unsafe classes in otherwise permitted modules

Also known asGHSA-qcx9-j53g-ccgfPYSEC-2021-335PYSEC-2021-875

Published

Jul 30, 2021

Updated

Jul 9, 2026

Affected

4 pkgs

Patched

4 / 4

Exploits

None indexed

Exploitation data as of Oct 9, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗

2.0%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs81th percentile — riskier than 81% of all scored CVEsHighest risk

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

How urgent is this, really

CVE-2021-32807 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

4 pkgs affected

🐍accesscontrol🐍accesscontrol🐍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

The module AccessControl defines security policies for Python code used in restricted code within Zope applications. Restricted code is any code that resides in Zope's object database, such as the contents of Script (Python) objects.

The policies defined in AccessControl severely restrict access to Python modules and only exempt a few that are deemed safe, such as Python's string module. However, full access to the string module also allows access to the class Formatter, which can be overridden and extended within Script (Python) in a way that provides access to other unsafe Python libraries. Those unsafe Python libraries can be used for remote code execution.

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 4.3 and 5.2. Only AccessControl versions 4 and 5 are vulnerable, and only on Python 3, not Python 2.7.

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.

For more information

If you have any questions or comments about this advisory:

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

Affected Packages

4 total 4 fixed

Ecosystem	Package	Vulnerable range	Fix
🐍PyPI	`accesscontrol`	≥ 4.0&&< 4.3	4.3`pip install --upgrade 'accesscontrol==4.3'`
🐍PyPI	`accesscontrol`	≥ 5.0&&< 5.2	5.2`pip install --upgrade 'accesscontrol==5.2'`
🐍PyPI	`zope`	≥ 4.0&&< 4.3	4.3`pip install --upgrade 'zope==4.3'`
🐍PyPI	`zope`	≥ 5.0&&< 5.2	5.2`pip install --upgrade 'zope==5.2'`

Affected Products

1 product · 2 configurations

Application

accesscontrolzope

≥ 5.0 && < 5.2

range

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for accesscontrol, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update accesscontrol to 4.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-32807 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 The module `AccessControl` defines security policies for Python code used in restricted code within Zope applications. Restricted code is any code that resides in Zope's object database, such as the contents of `Script (Python)` objects. The policies defined in `AccessControl` severely restrict access to Python modules and only exempt a few that are deemed safe, such as Python's `string` module. However, full access to the `string` module also allows access to the class `Formatter`, which can be overridden and extended within `Script (Python)` in a way that provides access to othe