Local application crash via oversized username

Denial of service in Pidgin 2.13.0 allows local users to crash the client with an excessively long account username. During account creation, Pidgin accepts a 1,000-character username without adequate length handling, then crashes when the account is used to join a chat. Exploitation requires local access to create or modify an account and invoke Join Chat; the reported consequence is loss of that client process, not data disclosure or modification.