Firefox '''''does not''''' disable any security applications. In fact if a security application permitted that to happen, it wouldn't be worth using. Now if you are referring to Firefox disabling a Kaspersky add-on for Firefox, you need to contact Kaspersky and ask them why they can't follow Mozilla rules for the "signing" of add-ons that they made to work with Firefox. They should have been aware of the new "signing" requirements 8 or 9 months ago, and should have been prepared back in Firefox 40 or 41. https://support.mozilla.org/en-US/kb/add-on-signing-in-firefox