Kylie Jenner Cosmetics: Thieves Target Lip Kits

Kylie Jenner's lip kits are in such demand, fans are breaking the law to get a piece of the action.

A bunch of customers are demanding answers after various products they ordered were MIA when they opened the boxes ... this according to the Better Business Bureau.

According to the BBB, the boxes had "highly recognizable" Kylie labeling, which proved irresistible to thieves who found the boxes either en route or on doorsteps and mailboxes ... and they somehow got inside and pilfered the contents.

Kylie's people have talked to folks at the BBB and assured them they would solve or at least minimize the problem by making the labeling more low key.