Because it is discontinued, Adobe no longer issues security patches. Any newly discovered vulnerabilities remain open for hackers to exploit.
Let’s clear up a common confusion. There are actually two different Adobe products:
Adobe Shockwave Player (formerly Macromedia Shockwave) was a pioneering web browser plugin used to display interactive multimedia, complex 3D graphics, and online games. While often confused with Adobe Flash, it was a distinct technology tailored for high-end web applications. Core Technology and History