Are there known security issues with Zend Opcache?
A Linode user has asked:
After setting up a new Linode we noticed that Zend Opcache is enabled by default. We like the idea of keeping it on, but are there any security concerns with using Opcache? Any known performance issues?
Zend OpCache is a caching engine that comes with php(1) by default (since php 5.5). It is a caching engine that stores pre-compiled php(1) code in memory which ultimately results in performance increase as the code does not have to be fully recompiled on each new request. The degree to which these performance improvements are noticeable depends on how busy your site is. The busier your site, the more noticeable the effects of OpCache are.
Since the cache maintained by OpCache is kept in your local memory, there is no security risk with using it…beyond the innate risk that php(1) can operate as an internet server.