Design documents with matching document IDs, from databases on the same cluster, may share a mutable Javascript environment when using these design document functions: * validate_doc_update * list * filter * filter views (using view functions as filters) * rewrite * update This doesn't affect map/reduce or search (Dreyfus) index functions. Users are recommended to upgrade to a version that is no longer affected by this issue (Apache CouchDB 3.3.2 or 3.2.3). Workaround: Avoid using design documents from untrusted sources which may attempt to cache or store data in the Javascript environment.