{"id":"GHSA-qcx9-j53g-ccgf","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)","aliases":["CVE-2021-32807","PYSEC-2021-335","PYSEC-2021-875"],"modified":"2026-07-09T16:56:14.762787976Z","published":"2021-08-05T17:01:30Z","related":["CVE-2021-32811"],"database_specific":{"severity":"MODERATE","github_reviewed":true,"github_reviewed_at":"2021-08-02T23:00:00Z","nvd_published_at":"2021-07-30T22:15:00Z","cwe_ids":["CWE-1321","CWE-915"]},"references":[{"type":"WEB","url":"https://github.com/zopefoundation/AccessControl/security/advisories/GHSA-qcx9-j53g-ccgf"},{"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/AccessControl/commit/b42dd4badf803bb9fb71ac34cd9cb0c249262f2c"},{"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"},{"type":"WEB","url":"https://github.com/zopefoundation/AccessControl/blob/master/CHANGES.rst#51-2021-07-30"}],"affected":[{"package":{"name":"accesscontrol","ecosystem":"PyPI","purl":"pkg:pypi/accesscontrol"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"4.0"},{"fixed":"4.3"}]}],"versions":["4.0","4.1","4.2"],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2021/08/GHSA-qcx9-j53g-ccgf/GHSA-qcx9-j53g-ccgf.json"}},{"package":{"name":"accesscontrol","ecosystem":"PyPI","purl":"pkg:pypi/accesscontrol"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"5.0"},{"fixed":"5.2"}]}],"versions":["5.0","5.1"],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2021/08/GHSA-qcx9-j53g-ccgf/GHSA-qcx9-j53g-ccgf.json"}},{"package":{"name":"zope","ecosystem":"PyPI","purl":"pkg:pypi/zope"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"4.0"},{"fixed":"4.3"}]}],"versions":["4.0","4.1","4.1.1","4.1.2","4.1.3","4.2","4.2.1"],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2021/08/GHSA-qcx9-j53g-ccgf/GHSA-qcx9-j53g-ccgf.json"}},{"package":{"name":"zope","ecosystem":"PyPI","purl":"pkg:pypi/zope"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"5.0"},{"fixed":"5.2"}]}],"versions":["5.0","5.1","5.1.1","5.1.2"],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2021/08/GHSA-qcx9-j53g-ccgf/GHSA-qcx9-j53g-ccgf.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:N/I:H/A:N"},{"type":"CVSS_V4","score":"CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N"}]}