Catalyzes RNA cleavage releasing a product with a 2',3'-cyclic phosphate at the 3'-end. a ribonucleotidyl-ribonucleotide-RNA = a 3'-end 2',3'-cyclophospho-ribonucleotide-RNA + a 5'-end dephospho-ribonucleoside-RNA Monomer. Belongs to the ENDOU family. Truncated N-terminus. Extended N-terminus.