A Supergirl movie from Warner Bros. and DC is in the works and Oren Uziel, known for writing the screenplays for 22 Jump Street and The Cloverfield Paradox, is working on the script.
This news comes from Deadline, and little else is known about the project. It does not currently have a producer, director or actors attached to it at this point, so it is likely in the very early stages of development.
Supergirl, also known by her Kryptonian name Kara Zor-El, is a well-known quantity in the DC universe and is the cousin of the Man of Steel himself. Kara was sent to Earth to protect her infant cousin, but was delayed and arrived after him.
Source: IGN.com Warner Bros. is Developing a Supergirl Movie