ArcadeDB before 26.8.1 (arcadedb-gremlin, affected <= 26.7.3) contains a remote code execution vulnerability in its Gremlin query engine. Although the engine defaults to the documented-secure java (gremlin-lang) engine, ArcadeGremlin.executeStatement() silently falls back to the insecure Groovy engine whenever a request carries any query parameter and the query does not parse as gremlin-lang. An authenticated user with any database role, including a read-only reader, can submit a parameterized Gremlin query to trigger the Groovy fallback and execute arbitrary operating system commands as the ArcadeDB server process user.