CVE-2021-32806 is a medium-severity (CVSS 6.1) Open Redirect vulnerability in products-isurlinportal. A fix is available for products-isurlinportal — see the affected versions and patch details below.
URL Redirection to Untrusted Site ('Open Redirect') in Products.isurlinportal
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
CVE-2021-32806 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.
Where this sits among everything scored
Of 385,987 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.
Real-World Exposure
products-isurlinportalReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.
Description
Impact
Various parts of Plone use the 'is url in portal' check for security, mostly to see if it is safe to redirect to a url. A url like https://example.org is not in the portal.
But the url https:example.org without slashes tricks our code and it is considered to be in the portal.
When redirecting, some browsers go to https://example.org, others give an error.
Attackers may use this to redirect you to their site, especially as part of a phishing attack.
Patches
The problem has been patched in Products.isurlinportal 1.2.0.
This is a recommended upgrade for all users of Plone 4.3 and 5, on Python 2.7 or higher.
It has not been tested on earlier Plone or Python versions.
Upcoming Plone 5.2.5 and higher will include the new version.
Discovered
This vulnerability was discovered and reported by Yuji Tounai of Mitsui Bussan Secure Directions, Inc. Thank you!
For more information
If you have any questions or comments about this advisory:
- Email the Plone Security Team at [email protected], especially when you think you have discovered a security problem or when you are not sure.
- Open an issue in the tracker if your question or comment can be public.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | products-isurlinportal | all versions | 1.2.0pip install --upgrade 'products-isurlinportal==1.2.0' |
Affected Products
isurlinportalploneDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for products-isurlinportal, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update products-isurlinportal to 1.2.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-32806 is resolved across your whole dependency graph.
Workarounds
Stop reflecting attacker-controlled destinations: resolve every redirect target against an allowlist of paths or hosts you own, prefer a server-side key over a full URL in the request, and reject absolute URLs entirely where the flow only ever needs a relative one.
Frequently Asked Questions
Is CVE-2021-32806 in your dependencies?
Find it across PyPI, including transitive dependencies.