The hidden-service feature in Tor before 0.3.0.8 allows a denial of service (assertion failure and daemon exit) in the relay_send_end_cell_from_edge_ function via a malformed BEGIN cell.
https://trac.torproject.org/projects/tor/ticket/22493
https://lists.torproject.org/pipermail/tor-announce/2017-June/000131.html
https://github.com/torproject/tor/commit/79b59a2dfcb68897ee89d98587d09e55f07e68d7