CVE-2021-21337
MEDIUMEPSS 95th pctlDescription
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".
How to fix
TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works
Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.
CVSS v3 Vector
Exploitability
Impact
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:N/A:N
Exploit Intelligence
High risk: more likely to be exploited than 95% of all known CVEs.
References
Related Vulnerabilities
Other CWE-601 (Open Redirect) vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2025-4123 | High | 7.6 | 97% | - | Fix |
| CVE-2018-11784 | Medium | 4.3 | 94% | - | Fix |
| CVE-2021-22881 | Medium | 6.1 | 87% | - | Fix |
| CVE-2022-45402 | Medium | 6.1 | 82% | - | Fix |
| CVE-2017-1000117 | High | 8.8 | 76% | - | Fix |
| CVE-2019-10098 | Medium | 6.1 | 74% | - | Fix |
Common questions
How do I fix CVE-2021-21337?
Upgrade products.pluggableauthservice to 2.6.1 or later.
Is CVE-2021-21337 being actively exploited?
Not that we know of. CVE-2021-21337 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 8.4% is the estimated probability that it will be exploited in the next 30 days. That is higher than 95% of all scored CVEs.
How severe is CVE-2021-21337?
CVE-2021-21337 has a CVSS v3 base score of 5.7, rated medium. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.
What does CVE-2021-21337 affect?
Published advisories record a fix for products.pluggableauthservice (NVD). Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.
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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2024-11-21.