vulnerability / NVI-00016042 / Revision 1
plone.restapi: Stored XSS by spoofing mime type
GitHub lists this reviewed advisory for plone.restapi, plone.restapi. Published version ranges and source prerequisites are shown below; this is not an inspection of a visitor’s application.
This report has not inspected your inventory, configuration, deployed build, reachability or evidence. A catalog listing and a severity score do not establish exposure or compromise.
01 / Meaning
Why it matters
Published affected context helps an owner decide what evidence to gather. This report has not examined your application.
4.3 medium
GitHub source severity; exploitability and local consequence require separate evidence.
As of · GitHub Advisory Database
02 / Applicability
The affected context
Affected versions, configuration prerequisites and known exclusions are public. Confirm each one against the deployed service.
plone.restapi
source listed< 9.15.6
### 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.restapi` to 9.15.6. * For Plone 6.2, upgrade `plone.restapi` to 10.0.1. This will prevent a
plone.restapi
source listed= 10.0.0
### 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.restapi` to 9.15.6. * For Plone 6.2, upgrade `plone.restapi` to 10.0.1. This will prevent a
03 / Response
What to do next
- investigate
Identify the exact component and deployed version, examine the linked publisher’s conditions, and retain evidence of any mitigation.
Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system. GitHub Advisory Database
A fixed release is not deployment evidence.
Check current vendor support and compatibility. After making a change, verify the deployed build and relevant runtime conditions. Keep the evidence, owner and time. An updated lockfile alone does not prove what is running.
04 / Limits
What this report cannot establish
- Customer inventory, deployment, reachability and exploitation have not been inspected.
05 / Provenance
Sources you can inspect
Each assertion retains its source. Mirrored records may repeat one underlying publisher; additional links are not independent corroboration.
- GHSA-8rqh-vxpr-x77p ↗
GitHub Advisory Database · vendor advisory
Observed . GitHub Advisory Database; CC-BY-4.0. Each advisory links its original attribution. Null normalizes fields.
Public revision history
Only published revisions appear here. Routine fetches do not create a material-change event.
- Revision 1 ·
First indexed by Null; source disclosure date is shown separately.