CVE-2021-32633: Remote Code Execution via traversal in TAL expressions
First published: Fri May 21 2021(Updated: )
### Impact Most Python modules are not available for using in TAL expressions that you can add through-the-web, for example in Zope Page Templates. This restriction avoids file system access, for example via the 'os' module. But some of the untrusted modules are available indirectly through Python modules that are available for direct use. By default, you need to have the Manager role to add or edit Zope Page Templates through the web. Only sites that allow untrusted users to add/edit Zope Page Templates through the web are at risk. ### Patches The problem has been fixed in Zope 5.2 and 4.6. ### Workarounds A site administrator can restrict adding/editing Zope Page Templates through the web using the standard Zope user/role permission mechanisms. Untrusted users should not be assigned the Zope Manager role and adding/editing Zope Page Templates through the web should be restricted to trusted users only. ### For more information If you have any questions or comments about this advisory: * Open an issue in the [Zope issue tracker](https://github.com/zopefoundation/Zope/issues) * Email us at [security@plone.org](mailto:security@plone.org)
Credit: security-advisories@github.com security-advisories@github.com
| Affected Software | Affected Version | How to fix |
|---|---|---|
| Plone Plone | <=4.3.20 | |
| Plone Plone | >=5.0<=5.2.4 | |
| Zope Zope | <4.6 | |
| Zope Zope | >=5.0<5.2 | |
| pip/Zope | >=5.0<5.2 | 5.2 |
| pip/Zope | <4.6 | 4.6 |
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Reference Links
- http://www.openwall.com/lists/oss-security/2021/05/21/1
- http://www.openwall.com/lists/oss-security/2021/05/22/1
- https://cyllective.com/blog/post/plone-authenticated-rce-cve-2021-32633/
- https://github.com/zopefoundation/Zope/commit/1f8456bf1f908ea46012537d52bd7e752a532c91
- https://github.com/zopefoundation/Zope/security/advisories/GHSA-5pr9-v234-jw36
- https://nvd.nist.gov/vuln/detail/CVE-2021-32633
- https://cyllective.com/blog/post/plone-authenticated-rce-cve-2021-32633
- https://github.com/pypa/advisory-database/tree/main/vulns/zope/PYSEC-2021-88.yaml
- https://github.com/advisories/GHSA-5pr9-v234-jw36 (Advisory)
Frequently Asked Questions
What is CVE-2021-32633?
CVE-2021-32633 is a vulnerability in Zope web application server that allows users to access untrusted modules indirectly.
How can the CVE-2021-32633 vulnerability be exploited?
The CVE-2021-32633 vulnerability can be exploited by accessing untrusted modules indirectly through Python modules available for direct use.
What is the severity of CVE-2021-32633?
The severity of CVE-2021-32633 is high, with a severity score of 8.8.
Which software versions are affected by CVE-2021-32633?
The affected software versions include Plone versions up to and including 4.3.20, Plone versions between 5.0 and 5.2.4, Zope versions up to 4.6, and Zope versions between 5.0 and 5.2.
How do I mitigate the CVE-2021-32633 vulnerability?
To mitigate the CVE-2021-32633 vulnerability, update your Zope and Plone installations to version 4.3.21 or above for Plone, and version 5.2.5 or above for Zope.
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