The fetchnews NNTP client in leafnode 1.11.2 and earlier can hang while waiting for input that never arrives, which allows remote NNTP servers to cause a denial of service (news loss).
fetchnews in leafnode 1.9.48 to 1.11.1 allows remote NNTP servers to cause a denial of service (crash) by closing the connection while fetchnews is reading (1) an article header or (2) an article body, which also prevents fetchnews from querying other servers.