They've had a way to blacklist loading DLLs for a very long time [0], by patching the call that loads DLLs. That rather basic approach got a little bit more so

They've had a way to blacklist loading DLLs for a very long time [0], by patching the call that loads DLLs. That rather basic approach got a little bit more sophisticated in 2019 as well - following an approach that Chrome took. [0] https://bugzilla.mozilla.org/show_bug.cgi?id=524904 https://bugzilla.mozilla.org/show_bug.cgi?id=524904