MFA is a strong front-door lock. But it’s not the only thing that decides whether someone can get in.
After you sign in, your browser keeps you logged in using a session token (often stored as a cookie). It’s the digital version of a wristband at an event: once you’ve been checked, the wristband proves you belong there. If an attacker steals that wristband, they may not need to beat your MFA prompt at all.
That’s the core of session cookie hijacking. The attacker isn’t “cracking” MFA. They’re skipping it by replaying your already authenticated session.
This isn’t a reason to stop using MFA. It’s a reason to stop treating MFA as the finish line.