What is CVE-2021-32811?

CVE-2021-32811 is a high-severity vulnerability in Zope Accesscontrol, classified under Improperly Controlled Modification of Dynamically-Determined Object Attributes. CVSS score: 7.5/10. Published 2021-08-02.

How severe is CVE-2021-32811?

High severity. CVSS v3 base score is 7.5 out of 10.

Prototype Pollution in Zope Accesscontrol

CVE-2021-32811

Zope is an open-source web application server. Zope versions prior to versions 4.6.3 and 5.3 have a remote code execution security issue. In order to be affected, one must use Python 3 for one's Zope deployment, run Zope 4 below version 4.6.3 or Zope 5 below version 5.3, and have the optional `Products.PythonScripts` add-on package installed. By default, one must 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 are at risk. Zope releases 4.6.3 and 5.3 are not vulnerable. As a workaround, 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.

Vulnerability class: Mass Assignment

Published 2021-08-02 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.023 (82.6th percentile), scored 2026-09-30.

Low probability of exploitation in the next 30 days, but still tracked. 83rd percentile — 82.6% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.023 · newest: 0.023 · change: +0.000

Affected products

Zope Accesscontrol
Zope
Zopefoundation Zope — versions >= 4.0, < 4.6.3, >= 5.0, < 5.3

Weakness classification (CWE)

References

github.com/zopefoundation/Zope/security/advisories/GHSA-g4gq-j4p2-j8fr (Third Party Advisory)
github.com/zopefoundation/AccessControl/security/advisories/GHSA-qcx9-j53g-ccgf (Third Party Advisory)
github.com/zopefoundation/Zope/commit/f72a18dda8e9bf2aedb46168761668464a4be988 (Patch, Third Party Advisory)

Frequently asked questions

What is CVE-2021-32811?: CVE-2021-32811 is a high-severity vulnerability in Zope Accesscontrol, classified under Improperly Controlled Modification of Dynamically-Determined Object Attributes. CVSS score: 7.5/10. Published 2021-08-02.
How severe is CVE-2021-32811?: High severity. CVSS v3 base score is 7.5 out of 10.