Rey Mysterio is currently working for WWE without a contract.
Dave Meltzer is reporting that Mysterio's latest WWE deal, signed in September 2018, has expired but that he is still working for WWE. Mysterio and his son, Dominik, have been heavily featured on Raw in a key storyline with Seth Rollins.
Meltzer reported in the latest Wrestling Observer Newsletter that Mysterio and Dominik were scheduled to appear in person on the June 29th Raw, but their segment was changed to a taped appearance from their home instead.
Meltzer also is reporting there was a plan to make a Mysterio vs. Rollins "eye for an eye" match for July 19th's Extreme Rules where the only way to win would be to take out your opponent's eye. As of now, that match has yet to be announced.
Mysterio, 45, worked high profile dates for NJPW and AAA between 2015 and his WWE return in 2018. He also worked the first All In for what is now known as AEW.