Volto is a ReactJS-based frontend for the Plone Content Management System. Versions 16.34.0 and below, 17.0.0 through 17.22.1, 18.0.0 through 18.27.1, and 19.0.0-alpha.1 through 19.0.0-alpha.5, an anonymous user could cause the NodeJS server part of Volto to quit with an error when visiting a specific URL. This issue is fixed in versions 16.34.1, 17.22.2, 18.27.2 and 19.0.0-alpha.6.
The product dereferences a pointer that it expects to be valid but is NULL.