CVE-2021-32633

Remote Code Execution via traversal in TAL expressions

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
• Email us at [email protected]

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.

Input manipulates file paths to reach files outside the intended directory, such as configuration or credential files. Typical impact: unauthorized file read or write outside the intended directory.

CVE-2021-32633 has a CVSS score of 6.8 (High). The vector is network-reachable, low privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (4.6, 5.2); upgrading removes the vulnerable code path.

Kodem intelligence

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The problem has been fixed in Zope 5.2 and 4.6.

1. What is CVE-2021-32633? CVE-2021-32633 is a high-severity path traversal vulnerability in Zope (pip), affecting versions < 4.6. It is fixed in 4.6, 5.2. Input manipulates file paths to reach files outside the intended directory, such as configuration or credential files.
2. How severe is CVE-2021-32633? CVE-2021-32633 has a CVSS score of 6.8 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of Zope are affected by CVE-2021-32633? Zope (pip) versions < 4.6 is affected.
4. Is there a fix for CVE-2021-32633? Yes. CVE-2021-32633 is fixed in 4.6, 5.2. Upgrade to this version or later.
5. Is CVE-2021-32633 exploitable, and should I be worried? Whether CVE-2021-32633 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2021-32633 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2021-32633?
   • Upgrade Zope to 4.6 or later
   • Upgrade Zope to 5.2 or later

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