Essentially, it allows calling eval[1] and executing "privileged loads"[0] in some elevated contexts (the System Principal, which is responsible for the browser

Essentially, it allows calling eval[1] and executing "privileged loads"[0] in some elevated contexts (the System Principal, which is responsible for the browser UI[2]). Those are useful mitigations, but disabling them for some custom user-chrome is unlikely to have a meaningful impact on your browser's security. [0] https://searchfox.org/mozilla-central/source/dom/security/nsContentSecurityManager.cpp#882 https://searchfox.org/mozilla-central/source/dom/security/ns... [1] https://searchfox.org/mozilla-central/source/dom/security/nsContentSecurityUtils.cpp#656 https://searchfox.org/mozilla-central/source/dom/security/ns... [2]: https://blog.mozilla.org/attack-and-defense/2020/06/10/understanding-web-security-checks-in-firefox-part-1/ https://blog.mozilla.org/attack-and-defense/2020/06/10/under...