This write-up is not helpful and says nothing about how one would be infected. it just says it can do code execution but no evidence anyone has been infected in any way or how would would be infected. The worst 0day possible is un-sandboxed code execution that is activated by merely visiting a webpage or clickinig.
https://www.forbes.com/sites/daveywinder/2019/03/07/google-c...
> Although information regarding CVE-2019-5786 remains scarce currently, Satnam Narang, a senior research engineer at Tenable, says it is a "Use-After-Free (UAF) vulnerability in FileReader, an application programming interface (API) included in browsers to allow web applications to read the contents of files stored on a user's computer." Some further digging by Catalin Cimpanu over at ZDNet suggests that there are malicious PDF files in the wild that are being used to exploit this vulnerability. "The PDF documents would contact a remote domain with information on the users' device --such as IP address, OS version, Chrome version, and the path of the PDF file on the user's computer" Cimpanu says. These could just be used for tracking purposes, but there is also the potential for more malicious behavior. The 'use-after-free' vulnerability is a memory corruption flaw that carries the risk of escalated privileges on a machine where a threat actor has modified data in memory through exploiting it.