wp-admin/async-upload.php in the media uploader in WordPress before 3.0.5 allows remote authenticated users to read (1) draft posts or (2) private posts via a modified attachment_id parameter.
http://codex.wordpress.org/Version_3.0.5
http://core.trac.wordpress.org/changeset/17393
http://lists.fedoraproject.org/pipermail/package-announce/2011-March/056412.html
http://lists.fedoraproject.org/pipermail/package-announce/2011-March/056998.html
http://lists.fedoraproject.org/pipermail/package-announce/2011-March/057003.html
http://openwall.com/lists/oss-security/2011/02/08/7
http://openwall.com/lists/oss-security/2011/02/09/13
http://secunia.com/advisories/43729
http://www.debian.org/security/2011/dsa-2190
http://www.securityfocus.com/bid/46249
http://www.vupen.com/english/advisories/2011/0658