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CVE-2021-21337

URL Redirection to Untrusted Site ('Open Redirect') in Products.PluggableAuthService

5.7 MediumPublic exploitFix available

Products.PluggableAuthService is a pluggable Zope authentication and authorization framework. In Products.PluggableAuthService before version 2.6.0 there is an open redirect vulnerability. A maliciously crafted link to the login form and login functionality could redirect the browser to a different website. The problem has been fixed in version 2.6.1. Depending on how you have installed Products.PluggableAuthService, you should change the buildout version pin to 2.6.1 and re-run the buildout, or if you used pip simply do `pip install "Products.PluggableAuthService>=2.6.1".

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
Low
Privileges needed
Low
User interaction
Required

What an attacker can affect

Confidentiality
High
Integrity
None
Availability
None

Exploit likelihood

8.44%Up 7.6 points since Apr 14, 2021
90%50%10%1%

What each source reports

CVE List Score used 5.7

URL Redirection to Untrusted Site ('Open Redirect') in Products.PluggableAuthService

Products.PluggableAuthService is a pluggable Zope authentication and authorization framework. In Products.PluggableAuthService before version 2.6.0 there is an open redirect vulnerability. A maliciously crafted link to the login form and login functionality could redirect the browser to a different website. The problem has been fixed in version 2.6.1. Depending on how you have installed Products.PluggableAuthService, you should change the buildout version pin to 2.6.1 and re-run the buildout, or if you used pip simply do `pip install "Products.PluggableAuthService>=2.6.1".

Record
CVE-2021-21337
CVSS 3.1
5.7 MediumCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:N/A:N
Weakness
CWE-601
Updated
2026-11-02
EUVDEUVD-2021-0201 5.7

Products.PluggableAuthService is a pluggable Zope authentication and authorization framework. In Products.PluggableAuthService before version 2.6.0 there is an open redirect vulnerability. A maliciously crafted link to the login form and login functionality could redirect the browser to a different website. The problem has been fixed in version 2.6.1. Depending on how you have installed Products.PluggableAuthService, you should change the buildout version pin to 2.6.1 and re-run the buildout, or if you used pip simply do `pip install "Products.PluggableAuthService>=2.6.1".

Record
EUVD-2021-0201
CVSS 3.1
5.7 MediumCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:N/A:N
Updated
2026-11-03
GitHub AdvisoriesGHSA-p44j-xrqg-4xrr 6.9

URL Redirection to Untrusted Site ('Open Redirect') in Products.PluggableAuthService

Impact

What kind of vulnerability is it? Who is impacted?

Open redirect vulnerability - a maliciously crafted link to the login form and login functionality could redirect the browser to a different website.

Patches

Has the problem been patched? What versions should users upgrade to?

The problem has been fixed in version 2.6.1. Depending on how you have installed Products.PluggableAuthService, you should change the buildout version pin to 2.6.1 and re-run the buildout, or if you used pip simply do pip install "Products.PluggableAuthService>=2.6.1"

Workarounds

Is there a way for users to fix or remediate the vulnerability without upgrading?

There is no workaround. Users are encouraged to upgrade.

References

Are there any links users can visit to find out more?

For more information

If you have any questions or comments about this advisory:

Record
GHSA-p44j-xrqg-4xrr
CVSS 4.0
6.9 MediumCVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N
CVSS 3.1
5.7 MediumCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:N/A:N
Weakness
CWE-601
Updated
2026-11-02
NVD 5.7

Products.PluggableAuthService is a pluggable Zope authentication and authorization framework. In Products.PluggableAuthService before version 2.6.0 there is an open redirect vulnerability. A maliciously crafted link to the login form and login functionality could redirect the browser to a different website. The problem has been fixed in version 2.6.1. Depending on how you have installed Products.PluggableAuthService, you should change the buildout version pin to 2.6.1 and re-run the buildout, or if you used pip simply do `pip install "Products.PluggableAuthService>=2.6.1".

Record
CVE-2021-21337
CVSS 3.1
5.7 MediumCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:N/A:N
CVSS 3.1
6.1 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
CVSS 2.0
5.8 MediumAV:N/AC:M/Au:N/C:P/I:P/A:N
Weakness
CWE-601
Updated
2026-11-02
OSV 6.1

Products.PluggableAuthService is a pluggable Zope authentication and authorization framework. In Products.PluggableAuthService before version 2.6.0 there is an open redirect vulnerability. A maliciously crafted link to the login form and login functionality could redirect the browser to a different website. The problem has been fixed in version 2.6.1. Depending on how you have installed Products.PluggableAuthService, you should change the buildout version pin to 2.6.1 and re-run the buildout, or if you used pip simply do `pip install "Products.PluggableAuthService>=2.6.1".

Record
CVE-2021-21337
CVSS 3.1
6.1 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
Updated
2026-11-02
OSVGHSA-p44j-xrqg-4xrr 6.9

URL Redirection to Untrusted Site ('Open Redirect') in Products.PluggableAuthService

Impact

What kind of vulnerability is it? Who is impacted?

Open redirect vulnerability - a maliciously crafted link to the login form and login functionality could redirect the browser to a different website.

Patches

Has the problem been patched? What versions should users upgrade to?

The problem has been fixed in version 2.6.1. Depending on how you have installed Products.PluggableAuthService, you should change the buildout version pin to 2.6.1 and re-run the buildout, or if you used pip simply do pip install "Products.PluggableAuthService>=2.6.1"

Workarounds

Is there a way for users to fix or remediate the vulnerability without upgrading?

There is no workaround. Users are encouraged to upgrade.

References

Are there any links users can visit to find out more?

For more information

If you have any questions or comments about this advisory:

Record
GHSA-p44j-xrqg-4xrr
CVSS 4.0
6.9 MediumCVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N
CVSS 3.1
5.7 MediumCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:N/A:N
Weakness
CWE-601
Updated
2026-11-02
OSVPYSEC-2021-45 No score

Products.PluggableAuthService is a pluggable Zope authentication and authorization framework. In Products.PluggableAuthService before version 2.6.0 there is an open redirect vulnerability. A maliciously crafted link to the login form and login functionality could redirect the browser to a different website. The problem has been fixed in version 2.6.1. Depending on how you have installed Products.PluggableAuthService, you should change the buildout version pin to 2.6.1 and re-run the buildout, or if you used pip simply do `pip install "Products.PluggableAuthService>=2.6.1".

Record
PYSEC-2021-45
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
products-pluggableauthservice
PyPI
 before 2.6.1
2.6.1
products-pluggableauthservice
PyPI
 before 2.6.1, plus listed versions
1.10.01.11.01.11.11.11.21.11.3
Show 40 moreShow less
1.5.21.5.2.11.5.31.5.41.5.51.61.6.11.6.21.6.31.6.41.6.51.7.01.7.0b11.7.0b21.7.11.7.21.7.31.7.41.7.51.7.61.7.71.7.81.8.01.9.02.02.0b12.0b22.0b32.0b42.0b52.0b62.12.1.12.22.2.12.32.42.52.5.12.6.0
2.6.1
products-pluggableauthservice
PyPI
 before 2.6.1, plus listed versions
1.5.21.5.2.11.5.31.5.41.5.5
Show 40 moreShow less
1.61.6.11.6.21.6.31.6.41.6.51.7.0b11.7.0b21.7.01.7.11.7.21.7.31.7.41.7.51.7.61.7.71.7.81.8.01.9.01.10.01.11.01.11.11.11.21.11.32.0b12.0b22.0b32.0b42.0b52.0b62.02.12.1.12.22.2.12.32.42.52.5.12.6.0
2.6.1

Public exploits

Links only. Every CVE stores no exploit code.

Public exploits
SourceLinkDate
Exploit-DBProducts.PluggableAuthService 2.6.0 - Open Redirect2021-06-02

History

History
RecordedChangedSources
aliasesEUVD
first indexedCVE List, Exploit-DB, GitHub Advisories, NVD, OSV

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

In short

CVE-2021-21337 is a medium vulnerability (CVSS 5.7) in Zope Products.pluggableauthservice, published March 8, 2021. Public exploit code exists. EPSS puts the chance of exploitation in the next 30 days at 8.44%, the 95th percentile. Fixed in products-pluggableauthservice 2.6.1.

References

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