Vanilla extract in Islam is Halal or haram, the answer to this depends on its ingredients and how it was prepared. The following are the most obvious examples:

Vanilla extract usually contains alcohol, because traditional vanilla was created by macerating and percolating vanilla beans in a solution containing ethanol and water. The alcohol in the ethanol holds particular significance because Islam prohibits drinking alcohol. But that will depend on the alcohol type and also at least partly the volume of it.

Origin of the alcohol: If the vanilla extract contains alcohol that is not derived from wine and it has been added to a dish in small quantities so as not to be intoxicating then some Muslim scholars permit its use (halal). The alcohol serves as a solvent and evaporates.