WordPress before 2.6.2 does not properly handle MySQL warnings about insertion of username strings that exceed the maximum column width of the user_login column, and does not properly handle space characters when comparing usernames, which allows remote attackers to change an arbitrary user's password to a random value by registering a similar username and then requesting a password reset, related to a "SQL column truncation vulnerability." NOTE: the attacker can discover the random password ...

More... (http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2008-4106)