All extensions disabled due to expiration of intermediate signing cert

To re-enable all disabled non-system addons you can do the following. I am not responsible if this fucks up your install:

Open the browser console by hitting ctrl-shift-j

Copy and paste the following code, hit enter. Until mozilla fixes the problem you will need to redo this once every 24 hours:

    // Re-enable *all* extensions

    async function set_addons_as_signed() {
        Components.utils.import("resource://gre/modules/addons/XPIDatabase.jsm");
        Components.utils.import("resource://gre/modules/AddonManager.jsm");
        let addons = await XPIDatabase.getAddonList(a => true);

        for (let addon of addons) {
            // The add-on might have vanished, we'll catch that on the next startup
            if (!addon._sourceBundle.exists())
                continue;

            if( addon.signedState != AddonManager.SIGNEDSTATE_UNKNOWN )
                continue;

            addon.signedState = AddonManager.SIGNEDSTATE_NOT_REQUIRED;
            AddonManagerPrivate.callAddonListeners("onPropertyChanged",
                                                    addon.wrapper,
                                                    ["signedState"]);

            await XPIDatabase.updateAddonDisabledState(addon);

        }
        XPIDatabase.saveChanges();
    }

    set_addons_as_signed();

Edit: Cleanup up code slightly...

I wonder how long until the "security vultures" come upon this workaround and stop it from working... would be ironic if that happened sooner than the expired cert getting fixed.

Seems unlikely. If you’re willing and able to run code like the above, sourced from a random comment on the Internet, there’s no amount of security vulture that’s going to protect you from skillfully making your Internet experience unsafe for yourself.