WordPress is a PHP and MySQL based multiuser blogging system.
"random" discovered that users can enter serialized objects as strings in their profiles that will be harmful when unserialized. "adapter" found out that user-edit.php fails to effectively deny non-permitted users access to other user's metadata. Additionally, a directory traversal vulnerability in the wp-db-backup module was discovered.
By entering specially crafted strings in his profile, an attacker can crash PHP or even the web server running WordPress. Additionally, by crafting a simple URL, an attacker can read metadata of any other user, regardless of their own permissions. A user with the permission to use the database backup plugin can possibly overwrite files he otherwise has no access to.
There is no known workaround at this time.
All WordPress users should upgrade to the latest version:
# emerge --sync
# emerge --ask --oneshot --verbose ">=www-apps/wordpress-2.0.5"