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CVE-2021-32633

Remote Code Execution via traversal in TAL expressions

6.8 MediumFix available

Zope is an open-source web application server. In Zope versions prior to 4.6 and 5.2, users can access untrusted modules indirectly through Python modules that are available for direct use. By default, only users with the Manager role can add or edit Zope Page Templates through the web, but sites that allow untrusted users to add/edit Zope Page Templates through the web are at risk from this vulnerability. The problem has been fixed in Zope 5.2 and 4.6. As a workaround, 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.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
High
Privileges needed
Low
User interaction
None

What an attacker can affect

Confidentiality
High
Integrity
High
Availability
None

Exploit likelihood

1.86%Up 1.0 points since May 22, 2021
90%50%10%1%

What each source reports

CVE List Score used 6.8

Remote Code Execution via traversal in TAL expressions

Zope is an open-source web application server. In Zope versions prior to 4.6 and 5.2, users can access untrusted modules indirectly through Python modules that are available for direct use. By default, only users with the Manager role can add or edit Zope Page Templates through the web, but sites that allow untrusted users to add/edit Zope Page Templates through the web are at risk from this vulnerability. The problem has been fixed in Zope 5.2 and 4.6. As a workaround, 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.

Record
CVE-2021-32633
CVSS 3.1
6.8 MediumCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N
Weakness
CWE-22
Updated
2026-11-02
EUVDEUVD-2021-0471 6.8

Zope is an open-source web application server. In Zope versions prior to 4.6 and 5.2, users can access untrusted modules indirectly through Python modules that are available for direct use. By default, only users with the Manager role can add or edit Zope Page Templates through the web, but sites that allow untrusted users to add/edit Zope Page Templates through the web are at risk from this vulnerability. The problem has been fixed in Zope 5.2 and 4.6. As a workaround, 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.

Record
EUVD-2021-0471
CVSS 3.1
6.8 MediumCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N
Updated
2026-11-03
GitHub AdvisoriesGHSA-5pr9-v234-jw36 7.6

Remote Code Execution via traversal in TAL expressions

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:

Record
GHSA-5pr9-v234-jw36
CVSS 4.0
7.6 HighCVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N
CVSS 3.1
6.8 MediumCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N
Weakness
CWE-22
Updated
2026-11-02
GitHub AdvisoriesGHSA-962m-m8jw-8wrr 8.8

Duplicate Advisory: Path Traversal in Zope

Duplicate Advisory

This advisory has been withdrawn because it is a duplicate of GHSA-5pr9-v234-jw36. This link is maintained to preserve external references.

Original Description

Zope is an open-source web application server. In Zope versions prior to 4.6 and 5.2, users can access untrusted modules indirectly through Python modules that are available for direct use. By default, only users with the Manager role can add or edit Zope Page Templates through the web, but sites that allow untrusted users to add/edit Zope Page Templates through the web are at risk from this vulnerability. The problem has been fixed in Zope 5.2 and 4.6. As a workaround, 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.

Record
GHSA-962m-m8jw-8wrr
CVSS 3.1
8.8 HighCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Weakness
CWE-22
Updated
2026-11-02
NVD 6.8

Zope is an open-source web application server. In Zope versions prior to 4.6 and 5.2, users can access untrusted modules indirectly through Python modules that are available for direct use. By default, only users with the Manager role can add or edit Zope Page Templates through the web, but sites that allow untrusted users to add/edit Zope Page Templates through the web are at risk from this vulnerability. The problem has been fixed in Zope 5.2 and 4.6. As a workaround, 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.

Record
CVE-2021-32633
CVSS 3.1
6.8 MediumCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N
CVSS 3.1
8.8 HighCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CVSS 2.0
6.5 MediumAV:N/AC:L/Au:S/C:P/I:P/A:P
Weakness
CWE-22
Updated
2026-11-02
OSV 8.8

Zope is an open-source web application server. In Zope versions prior to 4.6 and 5.2, users can access untrusted modules indirectly through Python modules that are available for direct use. By default, only users with the Manager role can add or edit Zope Page Templates through the web, but sites that allow untrusted users to add/edit Zope Page Templates through the web are at risk from this vulnerability. The problem has been fixed in Zope 5.2 and 4.6. As a workaround, 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.

Record
CVE-2021-32633
CVSS 3.1
8.8 HighCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Updated
2026-11-02
OSVGHSA-5pr9-v234-jw36 7.6

Remote Code Execution via traversal in TAL expressions

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:

Record
GHSA-5pr9-v234-jw36
CVSS 4.0
7.6 HighCVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N
CVSS 3.1
6.8 MediumCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N
Weakness
CWE-22
Updated
2026-11-02
OSVGHSA-962m-m8jw-8wrr 8.8

Duplicate Advisory: Path Traversal in Zope

Duplicate Advisory

This advisory has been withdrawn because it is a duplicate of GHSA-5pr9-v234-jw36. This link is maintained to preserve external references.

Original Description

Zope is an open-source web application server. In Zope versions prior to 4.6 and 5.2, users can access untrusted modules indirectly through Python modules that are available for direct use. By default, only users with the Manager role can add or edit Zope Page Templates through the web, but sites that allow untrusted users to add/edit Zope Page Templates through the web are at risk from this vulnerability. The problem has been fixed in Zope 5.2 and 4.6. As a workaround, 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.

Record
GHSA-962m-m8jw-8wrr
CVSS 3.1
8.8 HighCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Weakness
CWE-22
Updated
2026-11-02
OSVPYSEC-2021-88 No score

Zope is an open-source web application server. In Zope versions prior to 4.6 and 5.2, users can access untrusted modules indirectly through Python modules that are available for direct use. By default, only users with the Manager role can add or edit Zope Page Templates through the web, but sites that allow untrusted users to add/edit Zope Page Templates through the web are at risk from this vulnerability. The problem has been fixed in Zope 5.2 and 4.6. As a workaround, 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.

Record
PYSEC-2021-88
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
zope
PyPI
before 4.6
4.6
zope
PyPI
5.0 up to 5.2
5.2
zope
PyPI
before 4.6, plus listed versions
4.04.0b14.0b104.0b24.0b3
Show 24 moreShow less
4.0b44.0b54.0b64.0b74.0b84.0b94.14.1.14.1.24.1.34.24.2.14.34.44.4.14.4.24.4.34.4.44.54.5.14.5.24.5.34.5.44.5.5
4.6
zope
PyPI
5.0 up to 5.2, plus listed versions
5.15.1.15.1.2
5.2
zope
PyPI
before 4.6, 5.0 up to 5.2, plus listed versions
4.04.0b14.0b104.0b24.0b3
Show 27 moreShow less
4.0b44.0b54.0b64.0b74.0b84.0b94.14.1.14.1.24.1.34.24.2.14.34.44.4.14.4.24.4.34.4.44.54.5.14.5.24.5.34.5.44.5.55.15.1.15.1.2
4.65.2

History

History
RecordedChangedSources
affected
aliasesEUVD
first indexedCVE List, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2021-32633 is a medium vulnerability (CVSS 6.8) in Zope, published May 21, 2021. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 1.86%, the 79th percentile. Fixed in zope 4.6.

References

Show 4 moreShow less
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