CVE-2021-35959 — plone
MEDIUMCVE-2021-35959 is a medium-severity (CVSS 5.4) Cross-site Scripting (XSS) vulnerability in plone. The records list no fixed version yet; check the vendor advisory below and apply the mitigations in the meantime.
Plone has stored XSS in folder contents
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
Real-World Exposure
ploneReal-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
In Plone 5.0 through 5.2.4, Editors are vulnerable to XSS in the folder contents view, if a Contributor has created a folder with a SCRIPT tag in the description field.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | plone | ≥ 5.0 | No fix |
Affected Products
ploneploneDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for plone, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Remediation status
The records we use list no patched version of plone for CVE-2021-35959. Check the maintainer's advisory, and where your build allows, override or pin the dependency away from the vulnerable range.
Mitigate without a patch
Escape or sanitise the affected output on the server side rather than relying on client-side filtering, and add a Content-Security-Policy that blocks inline script execution so injected markup cannot run even if it reaches the page.
Frequently Asked Questions
Is CVE-2021-35959 in your dependencies?
Find it across PyPI, including transitive dependencies.