EdgeHTML is the rendering engine of the Edge browser in Windows 10. It is a fork of the MSHTML/Trident rendering engine currently used in Internet Explorer. The forking was done to support modern Web standards and remove legacy code. Microsoft estimated that around 220,000-plus lines of code were removed, while over 300,000 lines were added for interoperability fixes and new features. The attack surface of a rendering engine is quite extensive due to the number of different file types it needs to process.”]
Source: https://securityintelligence.com/understanding-edgehtmls-attack-surface-and-exploit-mitigations/