Abstract We obtain finite-temperature M2 black branes in 11-dimensional supergravity, in a G 4-flux background whose self-dual part approaches a solution of Cvetič, Gibbons, Lü, and Pope, based upon Stenzel’s family of Ricci-flat Kähler deformed cones. Our solutions are asymptotically AdS 4 times a 7-dimensional Stiefel manifold V 5,2, and the branes are "smeared" to retain SO(5) symmetry in the internal space. The solutions represent a mass deformation of the corresponding dual CFT 3, whose full description is at this time only partially-understood. We investigate the possibility of a confinement/de-confinement phase transition analogous to the AdS 5 × S 5 case, and a possible Gregory-Laflamme type instability which could lead to polarised brane solutions which break SO(5). We discuss possible consequences for AdS/CFT and the KKLT cosmological uplift mechanism.