wp-login.php in WordPress 2.8.3 and earlier allows remote attackers to force a password reset for the first user in the database, possibly the administrator, via a key[] array variable in a resetpass (aka rp) action, which bypasses a check that assumes that $key is not an array.

References

• https://nvd.nist.gov/vuln/detail/CVE-2009-2762
• https://exchange.xforce.ibmcloud.com/vulnerabilities/52382
• http://archives.neohapsis.com/archives/fulldisclosure/2009-08/0114.html
• http://core.trac.wordpress.org/changeset/11798
• http://secunia.com/advisories/36237
• http://wordpress.org/development/2009/08/2-8-4-security-release/
• http://www.exploit-db.com/exploits/9410
• http://www.securityfocus.com/bid/36014
• http://www.securitytracker.com/id?1022707