Puccinia behenis is a rust fungus that affects the leaves of various Silene (Campion) species.  There is no host plant alternation, and only uredinia and blackish-brown telia are produced, on both sides of the leaves.  It is not considered to be a gall-causer (Redfern & Shirley, 2023). 

The teliospores are two-celled and on a short pedicel that is not persistent; the apical wall of the top cell is not thickened, unlike P arenariae.

Puccinia arenariae also on Campions, and almost identical in the field; microscopic examination of teliospores is needed

host/microscopy

Photograph the rust on the host.  Ensure you have noted the host-plant species in your comments.  If the rust is on campion, microscopic examination is needed.

Mostly on Campion (Silene)