PHP remote file inclusion vulnerability in includes/log.inc.php in Telekorn SignKorn Guestbook (SL) 1.3 and earlier, when register_globals is enabled and _SESSION[permission] parameter is set to "yes", allows remote attackers to execute arbitrary PHP code via a URL in the dir_path parameter.
https://www.exploit-db.com/exploits/2354
https://exchange.xforce.ibmcloud.com/vulnerabilities/28888
http://www.vupen.com/english/advisories/2006/3570