Ell flashing bridges the transition from the roof’s surface and a wall or upright surface such as a curb. The ell flashing has not been sealed properly and the shingles are pealing back from the flashing allowing seepage. This can be correctly by removing the area and installing mastic sealant correctly. New membrane may need to be installed in this area. Also, if the ell flashing cannot be cleaned or has too many old fastener holes in it, the entire flashings detail area may need to be replaced.