Web cache poisoning has long been an elusive vulnerability, a ‘theoretical’ threat used mostly to scare developers into obediently patching issues that nobody could actually exploit. In this paper I’ll show you how to compromise websites by using esoteric web features to turn their caches into exploit delivery systems, targeting everyone that makes the mistake of visiting their homepage.

Web cache poisoning is far from a theoretical vulnerability, and bloated applications and towering server stacks are conspiring to take it to the masses. We’ve seen that even well-known frameworks can hide dangerous omnipresent features, confirming it’s never safe to assume that someone else has read the source code just because it’s open-source and has millions of users. We’ve also seen how placing a cache in front of a website can take it from completely secure to critically vulnerable.

source: grugq