Well, not all RNA, though this discovery means all bases have been found in some capacity on multiple stellar bodies.
We have a 6th pseudo-base for tRNA which occasionally appears as the 3rd base pair in the transcription anticodons Inosine, which together with Uracil makes up something known as a wobble base pair.
Similar to how Uracil replaces Thymine in RNA, Inosine will replace Guanine, Adenine, Uracil, and Thymine. However, it only appears on the 3rd base of anticodons during transcription. This base pair is essential for transcription and redundancy