When a lethal alien is brought on board a spaceship by accident, the crew has to fight for their survival in order to escape

maybe

When a lethal alien is brought on board a spaceship, the small crew must to fight to the last man to avoid taking the monster back to earth.

ALIEN$

I agree with the previous penpusher. The beginning could also be something in the lines of "When accidentally bringing a lethal alien onboard the spaceship..."

Nice work, I need to rewatch this one. Maybe change out "the crew" to the main character?

In space no one can hear you in space.

Jokes aside, nice logline!
I'm thinking to tighten it, maybe you could write "when a lethal alien is found onboard a spaceship" instead?
Also, is no one the main character, do we follow the entire crew? Could someone hold the POV for the logline?