Kardashian Family Beefs Up Security After Paparazzi Breach -- But Something Stinks

Kim Kardashian and Kris Jenner have beefed up security at their Calabasas estate after a paparazzo allegedly trespassed onto their property, TMZ has learned -- but video footage of the incident makes the whole thing smell kinda fishy.

Kim posted the Blair-Witch-style video online yesterday, showing her mom running into their backyard ... in hot pursuit of the rogue photog. They say they even called the cops.

Sources close to the K-Klan tell us, the family has since hired round-the-clock security ... pretty crazy considering they already live in a gated community.

Now the fishy part ... If someone really was creeping around their property, why would a defenseless woman like Kim's mom run out to confront him ... especially a really rich defenseless woman?