4.5 Notice – Breaking changes in REST API due to bug

tl;dr: if you’re using wp_insert_* or *_post_meta in your REST APIREST API The REST API is an acronym for the RESTful Application Program Interface (API) that uses HTTP requests to GET, PUT, POST and DELETE data. It is how the front end of an application (think “phone app” or “website”) can communicate with the data store (think “database” or “file system”) https://developer.wordpress.org/rest-api/. callback, you need to ensure you are calling wp_slash() on data you are passing in, regardless of source.

Full post below:

REST API: Slashed Data in WordPress 4.4 and 4.5