The json.decode function in util/json.lua in Prosody 0.8.x before 0.8.1 might allow remote attackers to cause a denial of service (infinite loop) via invalid JSON data, as demonstrated by truncated data.
https://euvd.enisa.europa.eu/vulnerability/EUVD-2011-2515
http://prosody.im/doc/release/0.8.1