I have a custom module with a defined route as:
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:App/etc/routes.xsd">
<router id="standard">
<route id="custom_module" frontName="custom-module">
<module name="Custom_Module" />
</route>
</router>
</config>
With previous versions of Magento both GET and POST requests would work fine to http://mywebsite.com/custom-module/controllername
After upgrading to Magento 2.3.0, GET requests still work as before, however POST requests now do not call the execute() method of the controller. Instead, they respond with a 200 OK and a response body that is the homepage html of the website.
Does this have to do with some Csrf security feature and form keys that was added in v2.3?