The following undesired situations are possible:
- A blocked anonymous user (IP address) can perform all kind of edits on Wikidata: https://www.wikidata.org/wiki/Special:Contributions/84.81.160.164
- A blocked registered or anonymous user can edit Wikibase entities: https://www.wikidata.org/wiki/Special:Contributions/Abian, https://www.wikidata.org/wiki/Special:Contributions/Crazykidd
Most of the identified accounts started to edit on November 30. See T210962.
Open questions:
- Is this behavior Wikidata.org specific? Is it in the Wikibase extension?
- Is T210830 the same?