The Marvel Cinematic Universe has a problem that may be bigger than Thanos, and that's the fact that Hulk actor Mark Ruffalo and Spider-Man actor Tom Holland seriously can't keep a secret.

Both actors have become infamous for spoiling Marvel films, with Ruffalo's mistake perhaps being the most notorious of all, when he stated in an interview that "everyone dies" at the end of Avengers: Infinity War.

It was such a mistake that co-star Don Cheadle recently joked he has refused to do press tours with Ruffalo again. While the Bruce Banner actor's reveal was the most talked about, Holland has been a repeat offender.

The 22-year-old actor spoiled the Spiderman: Far from Home title, he revealed that the first film, Homecoming, is part of a trilogy, accidentally spoiled Avengers: Infinity War to an entire theater, and he may have spoiled Avengers: Endgame due to his brief comments on the Quantum Realm.

The stars' inability to not drop spoilers may be a nuisance for some, but the reason neither can keep things confidential is really sweet.

In a recent interview with SYFY Wire, Evangeline Lilly, who plays the Wasp/Hope van Dyne in the MCU, says Ruffalo and Holland will let secrets slip because it's in their nature to be truthful.

“It’s no coincidence that it’s always Tom Holland and Mark Ruffalo because those two are such genuine, sweet, open, vulnerable human beings,” Lilly explained. “Their nature is not cagey or to hide, lie, and defend. They’re just lovers whose arms are wide open to the world."

Lilly also stated she has serious difficulty keeping spoilers to herself, too.

"Oh, I totally did [drop spoilers],” she revealed. “I got so lucky because it somehow magically got buried and no one ever heard about it. I was sweating bricks for about a week. Then I started breathing easier when I realized that nobody was going to see it. It’s hard not to slip up!”

Ruffalo, Holland and Lilly will appear in Avengers: Endgame when it's released on April 26.