The cookie authentication method in WordPress 2.5 relies on a hash of a concatenated string containing USERNAME and EXPIRY_TIME, which allows remote attackers to forge cookies by registering a username that results in the same concatenated string, as demonstrated by registering usernames beginning with "admin" to obtain administrator privileges, aka a "cryptographic splicing" issue. NOTE: this vulnerability exists because of an incomplete fix for CVE-2007-6013.

References

• https://nvd.nist.gov/vuln/detail/CVE-2008-1930
• https://exchange.xforce.ibmcloud.com/vulnerabilities/42027
• http://secunia.com/advisories/29965
• http://wordpress.org/development/2008/04/wordpress-251/
• http://www.cl.cam.ac.uk/users/sjm217/advisories/wordpress-cookie-integrity.txt
• http://www.securityfocus.com/archive/1/491356/100/0/threaded
• http://www.securityfocus.com/bid/28935
• http://www.securitytracker.com/id?1019923
• http://www.vupen.com/english/advisories/2008/1372/references