Direct static code injection vulnerability in index.php in Limesoft Guestbook (LS Simple Guestbook) 1.0 allows remote attackers to inject arbitrary PHP code into posts.txt via the message parameter.
https://www.exploit-db.com/exploits/3735
https://exchange.xforce.ibmcloud.com/vulnerabilities/33666
http://www.vupen.com/english/advisories/2007/1393
http://www.securityfocus.com/bid/23503
http://www.securityfocus.com/archive/1/465864/100/0/threaded