Maria Pavlovna, Grand Duchess of Saxe-Weimar-Eisenach by ? (Weimar Castle - Weimar, Thüringen Germany)
This could be a work by Joseph Karl Stieler who died in 1858 and stopped working for the Bavarian court in 1855. This portrait resembles one Stieler painted for the Saxe-Altenberg family in 1847-1848.
From Wikimedia; a linear flaw was removed from the curtain and spots were removed from her face and where the seam line on her shoulder ends with Photoshop by gogm.