CVE-2021-32807: Remote Code Execution via unsafe classes in otherwise permitted modules
Noroxi assessment
Priority: Monitor (action score 29/100)
- The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
- Probability of exploitation in the next 30 days: 2% (FIRST EPSS); higher than 81.1% of all records.
- Anyone who can reach it over the internet can trigger it. Administrator privileges are required. No user action is required. No special conditions are required; it is repeatable.
- Fixed version: accesscontrol (PyPI) 4.3, 5.2; zope (PyPI) 4.3, 5.2.
- Severity is disputed: the assigning authority (CNA) scores it 4.4, NVD 7.2.
Low priority for now. Upgrade to accesscontrol (PyPI) 4.3, 5.2; zope (PyPI) 4.3, 5.2 or later.
Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it
Primary sources: NVD · CVE.org · FIRST EPSS
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. 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. 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.
- Published
- Jul 30, 2021
- Updated
- Jun 16, 2026
- EPSS
- 2.0% · 81th percentile
- CWE
- CWE-915
Report tools
Action score
29
Monitor
Low priority for now.
- CVSS
- 28 / 40 · 7.2 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 1 / 30 · 2.0%
CNA vs NVD score
- NVD
- 7.2
- CNA · GitHub_M
- 4.4
- 2.8 point gap
CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:N/I:H/A:N
The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.
Get told when this record changes
- Not in KEV: no record of exploitation in the wild
- No public exploit code on record
- A fix has been released
If any of these changes, we'll tell you in the daily email digest.
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Noroxi analysis
What does it mean in your environment?
The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.
We use this product, ask for helpAffected systems
Is your version affected?
Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.
| Vendor | Product | CPE |
|---|---|---|
| zope | accesscontrol | cpe:2.3:a:zope:accesscontrol |
Affected versions
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- zope accesscontrol4.0 and later · before 4.3
- zope accesscontrol5.0 and later · before 5.2
Versions reported by the vendor
Affected version ranges reported by the assigning authority (GitHub_M). Independent of NVD's CPE analysis and usually ahead of it.
zopefoundation AccessControl
- >= 4.0, < 4.3, >= 5.0, < 5.2affected
Package-level exposure
OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.
| Ecosystem | Package | Affected range | Fix |
|---|---|---|---|
| PyPI | accesscontrol | from 4.0 · before 4.3 | 4.3 |
| PyPI | accesscontrol | from 5.0 · before 5.2 | 5.2 |
| PyPI | zope | from 4.0 · before 4.3 | 4.3 |
| PyPI | zope | from 5.0 · before 5.2 | 5.2 |
Same product
zope: all recordsOther highest-scoring records for the same primary product.
- CVE-2023-41050Information disclosure through Python's "format" functionality in Zope AccessControl30Monitor
- CVE-2021-32811Remote Code Execution via Script (Python) objects under Python 329Monitor
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
| Product / package | Fixed version | Source |
|---|---|---|
| PyPI:accesscontrol | 4.3 | Package registry (OSV) |
| PyPI:accesscontrol | 5.2 | Package registry (OSV) |
| PyPI:zope | 4.3 | Package registry (OSV) |
| PyPI:zope | 5.2 | Package registry (OSV) |
Exploit status
No known public exploit
No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.
Research context
For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.
Timeline
From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.
No dated events beyond publication.
No history yet (it accumulates with the daily EPSS job).
Patch and commit links
Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.
Credits
All researchersFinders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.
No credits in the CNA record.
Variant candidates
Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.
No nightly-computed relations.
Chain candidates
An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.
—
Bug bounty scope
No known public program.
Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).
Technical details
Attack conditions
- Anyone who can reach it over the internet can trigger it.
- Administrator privileges are required.
- No user action is required.
- No special conditions are required; it is repeatable.
If successful
- Confidentiality
- high · data can be read
- Integrity
- high · data or configuration can be modified
- Availability
- high · the service can be disrupted
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- High
- User interaction
- None
- Scope
- Unchanged
- Confidentiality impact
- High
- Integrity impact
- High
- Availability impact
- High
Weakness class (CWE)
CWE-915 · Improperly Controlled Modification of Dynamically-Determined Object AttributesCVSS vector
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
nvd-primary
Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
MITRE has no CAPEC/ATT&CK mapping for this CWE.
Change log
- Fix✗ → ✓
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References
Show all references (2 more)Show less
Vendor advisories and official records. Exploit/PoC links are deliberately left out.