&gt; Ok, I expected it should be feasible. I wasn&#x27;t optimistic when I read a Chrome bug that was nofix&#x27;d to make certificate info available to extensions.<p>This doesn&#x27;t seem like a thing you could easily do from an extension, especially from a Chrome extension.  But the browser itself easily has access to this information.<p>&gt; You sound kinda authoritative, are you suggesting that you could propose this change to firefox and it might get accepted?<p>No, not at all; I&#x27;m not a Firefox developer.  I just have strong opinions on how broken MITM is, and thoughts on how to mitigate it while dealing with the reality that an ultimatum to choose between the browser and the organizational policy will often see the browser lose.  Leaving the browser capable of browsing, while showing an unremovable information bar that warns people about something MITMing their traffic, seems like a strong step towards condemning MITM that might actually work.