The IndexedDatabaseManager class in the IndexedDB implementation in Mozilla Firefox before 39.0 and Firefox ESR 31.x before 31.8 and 38.x before 38.1 misinterprets an unspecified IDBDatabase field as a pointer, which allows remote attackers to execute arbitrary code or cause a denial of service (memory corruption and application crash) via unspecified vectors, related to a "type confusion" issue.