Unspecified vulnerability in phpBB allows remote authenticated users with Administration Panel access to execute arbitrary PHP code via crafted Font Colour 3 ($theme[fontcolor3] variable) and/or signature values, possibly involving the highlight functionality. NOTE: the original report does not clarify whether this issue is static code injection, eval injection, or another type of vulnerability.
https://exchange.xforce.ibmcloud.com/vulnerabilities/25889
http://www.securityfocus.com/archive/1/431387/100/0/threaded
http://www.securityfocus.com/archive/1/431015/100/0/threaded
http://www.debian.org/security/2006/dsa-1066
http://securityreason.com/securityalert/762
http://securityreason.com/securityalert/715