engine/lib/access.php in Elgg before 1.8.5 does not properly clear cached access lists during plugin boot, which allows remote attackers to read private entities via unspecified vectors.
https://exchange.xforce.ibmcloud.com/vulnerabilities/75757
http://www.securityfocus.com/bid/53623
http://secunia.com/advisories/49129
http://elgg.org/getelgg.php?forward=elgg-1.8.5.zip
http://blog.elgg.org/pg/blog/evan/read/209/elgg-185-released