CVE-2021-33513 — plone
MEDIUMCVE-2021-33513 is a medium-severity (CVSS 5.4) Cross-site Scripting (XSS) vulnerability in plone. No vendor fix is recorded yet; mitigation options are listed below.
Cross-site scripting in Plone
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
CVE-2021-33513 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.
Where this sits among everything scored
Of 385,738 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.
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
Plone through 5.2.4 allows XSS via the inline_diff methods in Products.CMFDiffTool.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | plone | all versions | 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
No patched version of plone has shipped for CVE-2021-33513 yet. Where your build allows, override or pin the dependency away from the vulnerable range, and apply any maintainer-recommended mitigation.
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-2021-33513 in your dependencies?
Find it across PyPI, including transitive dependencies.