I’m investigating certain 403 errors returned by CloudFront when I send PUT / POST data in JSON format to a custom Rest API. In a JSON field, the body data includes HTML tags (with properties and HTML content created by TinyMCE in a web).

I’m using postman to reproduce the behaviour, when I try to send the same content, the 403 is returned, but when I change the content to a simple HTML content with tags and properties or encode the original content using base-64, there’s no error.

Despite the body content that can be encoded using base-64, I don’t understand why CloudFront rejects the request in base of its contents. I dismiss the content lenght behaviour because normal content lenght is 919 bytes versus base-64 encoding content lenght of 427.76 KB. There’s a filter applied by default, or something like this?

Can someone helpme at this point?