If you are doing web application security assessments, you probably have seen many APIs that do not have any cross-site request forgery (CSRF) protections other than checking the Content-Type header.
Although this seems like a bad way of doing this, browsers do not normally allow you to use unusual Content-Type headers for another website (without CORS) and therefore the exploitation is quite impossible. However, a vulnerability was found in Internet Explorer and Edge that allowed users to set these arbitrary headers (anything that JavaScript can set). This issue was patched in July 2017. More details can be seen here:
As mentioned in the above URL, bypassing security features using redirection is a common attack vector and it was interesting that this issue had not been reported to Microsoft previously. A similar issue in Adobe Flash had been patched a long time ago (see https://www.whitehatsec.com/blog/flash-307-redirect-game-over/).