Executing a query on the production to fix erroring data

During the creation of some data on the production server by our backend, an unexpected error occurred and some data became inaccessible. Currently, a fix is being found for the error, but the flawed data is still on the server, causing some trouble. This can easily be fixed by setting some data to NULL. The question is, how should we handle this? Our backend uses the Spring framework and Liquibase to update the schema when necessary. Our production server is managed by a different company and is unaccessible for us (the developers). The other company wants us to write an entry for the Liquibase XML file to fix this. We are questioning this decision, but running a query on the production database seems tricky too.

Note: we are running more than just the production environment, so by adding the query to the Liquibase XML file, it will run on all environments.