The ability to override the new tab page was removed from Firefox quite a long time ago because it was constantly abused by other software that wanted to hijack the user's new tab page.

But, as you already said, you can still do it with a browser extension. I've personally used New Tab Override and find that it works very well. Because extensions handle new tab page changes differently, theoretically it's more difficult for an external program to change those settings.

Hope this helps.

So other software can hijack the new tab page but not the home page? Poor excuse for removing the new tab configuration instead of just applying the little effort to remove the vulnerabity.

No, software can take the homepage too (or most preferences for that matter). We see it all of the time here on the forums. However, it's a bit unreasonable to take away the ability to change the homepage at all.

It was more common to see software hijacking the new tab page because it's shown more often to the user and the new tab setting was somewhat hidden from the user.

Fortunately, the browser extensions are there to give you the same functionality. While I wouldn't say it's impossible for external software to hijack the new tab page when it's set with an extension, it's more difficult because of the way that it's handled compared to a standard Firefox preference.

See also:

• [/questions/1251199] How do I set my local HTML page as a homepage?