wp-admin/includes/post.php in WordPress before 3.6.1 allows remote authenticated users to spoof the authorship of a post by leveraging the Author role and providing a modified user_ID parameter.
codex.wordpress.org/Version_3.6.1
core.trac.wordpress.org/changeset/25321
lists.fedoraproject.org/pipermail/package-announce/2013-September/116828.html
lists.fedoraproject.org/pipermail/package-announce/2013-September/116832.html
lists.fedoraproject.org/pipermail/package-announce/2013-September/117118.html
wordpress.org/news/2013/09/wordpress-3-6-1/
www.debian.org/security/2013/dsa-2757