Security - Oj

# Security and Optimization¶ ↑

Two settings in Oj are useful for parsing but do expose a vulnerability if used from an untrusted source. Symbolized keys can cause memory to be filled with previous versions of ruby. Ruby 2.1 and below does not garbage collect Symbols. The same is true for auto defining classes in all versions of ruby; memory will also be exhausted if too many classes are automatically defined. Auto defining is a useful feature during development and from trusted sources but it allows too many classes to be created in the object load mode and auto defined is used with an untrusted source. The `Oj.strict_load()` method sets and uses the most strict and safest options. It should be used by developers who find it difficult to understand the options available in Oj.

The options in Oj are designed to provide flexibility to the developer. This flexibility allows Objects to be serialized and deserialized. No methods are ever called on these created Objects but that does not stop the developer from calling methods on them. As in any system, check your inputs before working with them. Taking an arbitrary `String` from a user and evaluating it is never a good idea from an unsecure source. The same is true for `Object` attributes as they are not more than `String`s. Always check inputs from untrusted sources.