GHSA-8rqh-vxpr-x77p
MEDIUMplone.restapi: Stored XSS by spoofing mime type
Blast Radius
plone-restapi🐍plone-restapiReal-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.
This is the same vulnerability as reported in plone.app.textfield:
https://github.com/plone/plone.app.textfield/security/advisories/GHSA-4r4f-gg25-rmg5
Patches
The problem has been patched:
- For Plone 6.0 and 6.2, upgrade
plone.restapito 9.15.6. - For Plone 6.2, upgrade
plone.restapito 10.0.1.
This will prevent abusing the REST API to store wrong rich text values.
This will not prevent XSS from rich text fields that already have wrong values. For that, you will need a patched plone.app.textfield version. See the plone.app.textfield advisory linked above for versions.
Workarounds
There is no known workaround.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | plone-restapi | all versions | 9.15.6 |
| 🐍PyPI | plone-restapi | ≥ 10.0.0&&< 10.0.1 | 10.0.1 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for plone-restapi. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update plone-restapi to 9.15.6 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-8rqh-vxpr-x77p is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether GHSA-8rqh-vxpr-x77p is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to GHSA-8rqh-vxpr-x77p. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-8rqh-vxpr-x77p in your dependencies?
O3 detects GHSA-8rqh-vxpr-x77p across PyPI dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.