{"id":"CVE-2021-32807","aliases":["GHSA-qcx9-j53g-ccgf","PYSEC-2021-335","PYSEC-2021-875"],"url":"https://o3.security/vulnerability/CVE-2021-32807","summary":"Remote Code Execution via unsafe classes in otherwise permitted modules","details":"### Impact\nThe 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. \n\nThe 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.\n\nBy 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.\n\n### Patches\nThe problem has been fixed in AccessControl 4.3 and 5.2.\nOnly AccessControl versions 4 and 5 are vulnerable, and only on Python 3, not Python 2.7.\n\n### Workarounds\nA 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.\n\n### For more information\nIf you have any questions or comments about this advisory:\n* Open an issue in the [AccessControl issue tracker](https://github.com/zopefoundation/AccessControl/issues)\n* Email us at [security@plone.org](mailto:security@plone.org)","published":"2021-07-30T22:15:07.967Z","modified":"2026-07-09T16:56:14.762787976Z","cvss":{"score":7.2,"severity":"HIGH","vector":"CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H"},"epss":null,"cisaKev":null,"exploitsKnown":null,"affectedPackages":[{"ecosystem":"PyPI","name":"accesscontrol","fixedVersion":"4.3"},{"ecosystem":"PyPI","name":"accesscontrol","fixedVersion":"5.2"},{"ecosystem":"PyPI","name":"zope","fixedVersion":"4.3"},{"ecosystem":"PyPI","name":"zope","fixedVersion":"5.2"}],"fix":{"url":"https://github.com/zopefoundation/AccessControl/commit/b42dd4badf803bb9fb71ac34cd9cb0c249262f2c","label":"zopefoundation/AccessControl@b42dd4b"},"references":[{"type":"ADVISORY","url":"https://github.com/zopefoundation/AccessControl/blob/master/CHANGES.rst#51-2021-07-30"},{"type":"ADVISORY","url":"https://github.com/zopefoundation/AccessControl/security/advisories/GHSA-qcx9-j53g-ccgf"},{"type":"FIX","url":"https://github.com/zopefoundation/AccessControl/commit/b42dd4badf803bb9fb71ac34cd9cb0c249262f2c"},{"type":"WEB","url":"https://github.com/zopefoundation/Zope/security/advisories/GHSA-g4gq-j4p2-j8fr"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2021-32807"},{"type":"WEB","url":"https://github.com/zopefoundation/AccessControl/commit/ae2dab0cc34e6dd1561c5b12d4a56cd140f87e1d"},{"type":"WEB","url":"https://github.com/zopefoundation/Zope/commit/869f947e586517566509e0ccdd4d99b60704cc02"},{"type":"WEB","url":"https://github.com/zopefoundation/Zope/commit/f72a18dda8e9bf2aedb46168761668464a4be988"},{"type":"WEB","url":"https://github.com/pypa/advisory-database/tree/main/vulns/accesscontrol/PYSEC-2021-335.yaml"},{"type":"WEB","url":"https://github.com/pypa/advisory-database/tree/main/vulns/accesscontrol/PYSEC-2021-370.yaml"},{"type":"WEB","url":"https://github.com/pypa/advisory-database/tree/main/vulns/zope/PYSEC-2021-368.yaml"},{"type":"WEB","url":"https://github.com/pypa/advisory-database/tree/main/vulns/zope/PYSEC-2021-875.yaml"},{"type":"PACKAGE","url":"https://github.com/zopefoundation/AccessControl"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-07-09T16:56:14.762787976Z"}}