I don't think there are any glitches yet and even if so you'll most likely end up getting reset for using them. I'd recommend trying the hardcore game modes. I tend to rank up extremely fast that way because I find it to be easier to play. Give it a shot!
No XP glitches that have been noted yet, however I'd recommend going and buying some Monster Energy with the X2 XP and then playing hardcore gamemodes! You should see yourself leveling up quite fast then
Hardcore game modes will be the fastest thing to level up as there aren’t any level up glitch. But I recommmend using many weapons and perks with versions attachments so you can get challenges unlocked witch will grant additional XP. Reason I recommmend hardcore is because most of the time you’ll get an additional 100xp for one shot kill bonuses