# CVE-2021-32807: Remote Code Execution via unsafe classes in otherwise permitted modules > Attackers with Manager role can execute arbitrary code via unsafe classes in permitted modules, requiring non-default web editing permissions. - **Severity:** Medium 4.4 (`CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:N/I:H/A:N`) - **Exploited in the wild:** Not known - **Login needed:** An administrator - **Attackable:** Over the internet - **Victim action needed:** Not needed - **Fix available:** Yes - **Published:** 30 Jul 2021 - **Updated:** 3 Aug 2024 - **Also known as:** GHSA-qcx9-j53g-ccgf, PYSEC-2021-335, PYSEC-2021-875 ## What is CVE-2021-32807? CVE-2021-32807 is a medium-severity code injection vulnerability in zopefoundation AccessControl, published on 30 Jul 2021. An attacker needs administrator access to exploit it, with no action from the victim. ### Official description 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. Weakness: CWE-1321 (Improperly Controlled Modification of Object Prototype Attributes), CWE-915 (Improperly Controlled Modification of Dynamically-Determined Object Attributes) ## Which versions are affected by CVE-2021-32807? 10 open source packages ship an affected version, including accesscontrol, AccessControl and zope. It affects 1 product. | Package | Ecosystem | Affected | Fixed in | | --- | --- | --- | --- | | `accesscontrol` | PyPI | From 4.0 | 4.3, 5.2 | | `accesscontrol` | PyPI | From 4.0 | 4.3 | | `accesscontrol` | PyPI | From 5.0 | 5.2 | | `AccessControl` | PyPI | From 4.0 | 4.3 | | `AccessControl` | PyPI | From 5.0 | 5.2 | | `zope` | PyPI | From 4.0 | 4.3, 5.2 | | `zope` | PyPI | From 4.0 | 4.3 | | `zope` | PyPI | From 4.0 | 4.3 | | `zope` | PyPI | From 5.0 | 5.2 | | `zope` | PyPI | From 5.0 | 5.2 | Products: Zope Accesscontrol. ## How do I fix CVE-2021-32807? Upgrade accesscontrol to a fixed version for your release line: 4.3 or 5.2. ## Is CVE-2021-32807 being exploited? There is no known exploitation of CVE-2021-32807 in the wild and no public exploit code. ## Other vulnerabilities in zopefoundation AccessControl - [CVE-2021-32811](https://insights.sbomify.com/CVE-2021-32811/): Remote Code Execution via Script (Python) objects under Python 3 (high 7.5) - [CVE-2023-41050](https://insights.sbomify.com/CVE-2023-41050/): Information disclosure through Python's "format" functionality in Zope AccessControl (medium 6.8) ## Fix prompt for AI coding agents ```text Check this codebase for CVE-2021-32807 and fix it if it is affected. What it is: CVE-2021-32807 is a medium-severity code injection vulnerability in zopefoundation AccessControl, published on 30 Jul 2021. An attacker needs administrator access to exploit it, with no action from the victim. Exploitation: There is no known exploitation of CVE-2021-32807 in the wild and no public exploit code. Affected packages and fixed versions: - accesscontrol (PyPI): affected from 4.0; fixed in 4.3, 5.2 - accesscontrol (PyPI): affected from 4.0; fixed in 4.3 - accesscontrol (PyPI): affected from 5.0; fixed in 5.2 - AccessControl (PyPI): affected from 4.0; fixed in 4.3 - AccessControl (PyPI): affected from 5.0; fixed in 5.2 - zope (PyPI): affected from 4.0; fixed in 4.3, 5.2 - zope (PyPI): affected from 4.0; fixed in 4.3 - zope (PyPI): affected from 4.0; fixed in 4.3 - zope (PyPI): affected from 5.0; fixed in 5.2 - zope (PyPI): affected from 5.0; fixed in 5.2 Task: 1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies. 2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it. 3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead. 4. Run the tests and summarise what changed and why. 5. If nothing in the project is affected, say so and change nothing. Reference: https://insights.sbomify.com/CVE-2021-32807/ (Markdown: https://insights.sbomify.com/CVE-2021-32807/index.md) ``` ## Sources - CVE record: https://www.cve.org/CVERecord?id=CVE-2021-32807 - NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-32807 - OSV: https://osv.dev/vulnerability/CVE-2021-32807 --- From sbomify Insights: https://insights.sbomify.com/CVE-2021-32807/ Summaries are generated and may contain mistakes; the official description above is the record.