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PYSEC-2026-3497

MediumCVSS 4.3 / 10
Published Jul 23, 2026·Last modified Jul 23, 2026
Affected Components(0)

No affected components available

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.textfield to 2.0.2.
  • For Plone 6.1, upgrade plone.app.textfield to 3.0.2.
  • For Plone 6.2, upgrade plone.app.textfield to 4.0.1.

Workarounds

There is no known workaround.

Risk Scores
Base Score
4.3

The vulnerability can be exploited over the network without needing physical access. It is easy for an attacker to exploit this vulnerability. An attacker needs basic access or low-level privileges. No user interaction is needed for the attacker to exploit this vulnerability. The impact is confined to the system where the vulnerability exists. There is a low impact on the confidentiality of the information.

Threat Intelligence
4.0

Exploitation attempts have been detected. Elevated vigilance and prompt remediation are advised.

EPSS
N/A

Probability that this vulnerability will be exploited in the wild within the next 30 days.

Exploit
Not available

We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.

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Medium severity
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