Versions Affected: All current Plone versions.
Versions Not Affected: None.
Nature of vulnerability: Allows creation of members by anonymous
users on sites that have self-registration enabled, allowing bypass
of CAPTCHA and similar protections against scripted attacks.
The patch can be added to buildouts as Products.PloneHotfix20150910
(available from PyPI) or downloaded from Plone.org.
Immediate Measures You Should Take: Disable self-registration until
you have applied the patch.