plone.app.textfield: Stored XSS by spoofing mime typeGHSA-4r4f-gg25-rmg5
MEDIUMGHSA-4r4f-gg25-rmg5 is a medium-severity (CVSS 4.3) CWE-80 vulnerability in plone-app-textfield. A fix is available for plone-app-textfield — see the affected versions and patch details below.
Exploitation Status
No confirmed exploitation observed yet
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for GHSA-4r4f-gg25-rmg5.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
GHSA-4r4f-gg25-rmg5 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.
Where this sits among everything scored
Of 395,249 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.
Real-World Exposure
plone-app-textfield🐍plone-app-textfield🐍plone-app-textfieldReal-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
A stored XSS affecting RichText fields. RichTextValue.output returns the raw, unsanitized stored value whenever the stored mimeType equals the outputMimeType. Because the safe-HTML output type (text/x-html-safe) is the type that signifies "already sanitized", any value whose stored mimeType equals it bypasses the safe_html transform entirely on render. The transform itself is sound — it correctly strips on* event-handler attributes and javascript:/data: URIs; the defect is that it is never invoked for these values. The unsanitized value is then emitted via tal:content="structure ...", which performs no escaping, so the payload executes in the viewer's browser.
This can be a problem when a RichText field is wrongly defined in code with a mimeType and outputMimeType that are the same, or when the REST API is used to the same effect.
Patches
The problem has been patched:
- For Plone 6.0, upgrade
plone.app.textfieldto 2.0.2. - For Plone 6.1, upgrade
plone.app.textfieldto 3.0.2. - For Plone 6.2, upgrade
plone.app.textfieldto 4.0.1.
Workarounds
There is no known workaround.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | plone-app-textfield | all versions | 2.0.2pip install --upgrade 'plone-app-textfield==2.0.2' |
| 🐍PyPI | plone-app-textfield | ≥ 3.0.0&&< 3.0.2 | 3.0.2pip install --upgrade 'plone-app-textfield==3.0.2' |
| 🐍PyPI | plone-app-textfield | ≥ 4.0.0&&< 4.0.1 | 4.0.1pip install --upgrade 'plone-app-textfield==4.0.1' |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for plone-app-textfield, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update plone-app-textfield to 2.0.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-4r4f-gg25-rmg5 is resolved across your whole dependency graph.
Workarounds
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 GHSA-4r4f-gg25-rmg5 in your dependencies?
Find it across PyPI, including transitive dependencies.