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Medium, CVSS 4.3amended

plone.app.textfield: Stored XSS by spoofing mime type

CVE-2026-54503GHSA-4r4f-gg25-rmg5

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (plone-app-textfield 4.0.1, 3.0.2, 2.0.2), redeploy, then verify what is actually installed.

This page has no inventory attached, so it cannot say whether you are affected. A vendor fix is not proof that your deployment is fixed.

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Affected packages

  • PyPI plone-app-textfield

    Affected
    < 2.0.2>= 3.0.0, < 3.0.2>= 4.0.0, <= 4.0.0
    Fixed in
    3.0.2, 2.0.2, 4.0.1

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS
4.3 · CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N
EPSS
  • CVE-2026-54503: 0.40% estimated exploitation activity in the next 30 days; percentile 34.35 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.
Source description

As published by the source; long descriptions are shortened.

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 safehtml 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.textfield to 2.0.2. For Plone 6.1, upgrade plone.app.textfield to 3.0.2. For…

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 2 · amended ·

    Amended from ghsa record GHSA-4r4f-gg25-rmg5

  2. Revision 1 · created ·

    Published from osv record GHSA-4r4f-gg25-rmg5

Agent brief

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# Patch Next advisory brief: CVE-2026-54503

Advisory: plone.app.textfield: Stored XSS by spoofing mime type
IDs: CVE-2026-54503, GHSA-4r4f-gg25-rmg5
Record: https://patchnext.com/advisories/cve-2026-54503 (revision 2, source checked 26 Oct 2026, 13:47 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 4.3)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: plone-app-textfield 4.0.1, 3.0.2, 2.0.2. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI plone-app-textfield: affected < 2.0.2; >= 3.0.0, < 3.0.2; >= 4.0.0, <= 4.0.0; fixed in 3.0.2, 2.0.2, 4.0.1

## Suggested inspection (read-only)
- `python -m pip show plone-app-textfield`: prints the installed version. Run with the environment that serves production active.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on plone-app-textfield.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-4r4f-gg25-rmg5 (OSV record GHSA-4r4f-gg25-rmg5 lists affected ranges: PyPI plone-app-textfield >=0 =3.0.0 =4.0.0 <4.0.1 (fixed))
- Verified: https://github.com/advisories/GHSA-4r4f-gg25-rmg5 (GitHub-reviewed advisory GHSA-4r4f-gg25-rmg5 lists affected ranges: PyPI plone-app-textfield >=0 =3.0.0 =4.0.0 <=4.0.0)

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