Plone fixes flaws allowing anonymous remote code execution

The Plone/Zope Security Team released hotfixes on 10 November 2026 to fix a chain of remote code execution flaws affecting Plone sites. The advisory states that the issues, collectively allowing an anonymous visitor to run code on the server, affect every supported release and older versions back to at least Plone 4.3.

Fixed packages cover Plone 6.2, 6.1 and 6.0, with corresponding updates to CMFPlone, CMFEditions, MimetypesRegistry, plone[.]batching and plone[.]restapi, and a standalone hotfix for older sites (Products.PloneHotfix20261110). Site operators are urged to update, restart Zope, and verify whether attackers have already modified versioning conditions.

The attack chain is described as a four-part sequence leading to unauthenticated code execution. The entry point is Products[.]CMFEditions (CVSS 9.8), where anonymous users can alter TALES conditions, titles or size limits, with those conditions later executing as code.

Escaping the sandbox is reported through restricted Python failures in modules such as Restricted Python, with Products[.]CMFPlone, Products[.]MimetypesRegistry and plone[.]batching exposing modules via allow_module, enabling restricted code to reach os and other modules (each advisory rated CVSS 9.1). A separate issue in plone[.]restapi (CVSS 4.7) could permit calls to protected methods on objects.

The CMFEditions advisory notes a working PoC exists, and the CMFEditions references suggest the details are public, with CVEs being requested and to be added later.

Affected versions include Plone 6.0, 6.1 and 6.2 prior to the fixed package versions, and older releases such as Plone 4.3, 5.0, 5.1 and 5.2 (which are out of support but indicated as affected). Mitigation guidance in the advisories recommends updating to the listed package versions (e.g., 6.2.3 for CMFPlone, 6.2.3/6.1.6/6.0.16 for respective lines) or applying the hotfix Products.PloneHotfix20261110, followed by a Zope restart and monitoring startup logs for “POSSIBLE ATTACK: MODIFIED VERSIONING CONDITIONS FOUND.”