ArcadeDB's Gremlin wire-protocol plugin (com.arcadedb:arcadedb-gremlin) in versions <= 26.7.3...

ArcadeDB's Gremlin wire-protocol plugin (com.arcadedb:arcadedb-gremlin) in versions <= 26.7.3 enforces authentication (SASL PLAIN) but performs no authorization: it never checks database access permissions (canAccessToDatabase) and never binds the authenticated principal into the engine. As a result, any valid server credential — even one provisioned for zero or one unrelated database — can read, write, and drop data in any database on the server by selecting a target database via a traversal-source alias, completely bypassing the engine's per-type/read-only/UPDATE_SCHEMA ACLs. The issue is fixed in version 26.8.1.