Prosody 0.8.x before 0.8.1, when MySQL is used, assigns an incorrect data type to the value column in certain tables, which might allow remote attackers to cause a denial of service (data truncation) by sending a large amount of data.
http://prosody.im/doc/release/0.8.1
http://hg.prosody.im/0.8/rev/d2406f0ce8a5