The Hollywood stars had gathered for the debut of David Cronenberg's new movie Map To The Stars on Monday (19May14) when an unexpected guest caused a stir.
A topless woman in a blonde wig, badly-applied lipstick and wearing just one shoe walked the red carpet, with tape bearing the world 'fragile' wrapped around her bottom half.
Fellow guests were spotted laughing at the spectacle, but it is not known if the movie's cast, which also includes Mia Wasikowska and John Cusack, were aware of the incident.
The woman posed for photographers before she was escorted away from the event by security guards. Her identity has not yet been revealed.
It is the latest prank to hit Cannes - Ukrainian journalist Vitalii Sediuk was detained by cops on Friday (16May14) after he dashed onto the red carpet and climbed under America Ferrera's long dress as she posed for photographers alongside her How to Train Your Dragon 2 castmates.