avatar_upload.asp in Avatar MOD 1.3 for Snitz Forums 3.4, and possibly other versions, allows remote attackers to bypass file type checks and upload arbitrary files via a null byte in the file name, as discovered by the Codescan product.
https://exchange.xforce.ibmcloud.com/vulnerabilities/26546
http://www.vupen.com/english/advisories/2006/1854
http://www.securityfocus.com/bid/18014
http://www.securityfocus.com/archive/1/434366/100/0/threaded
http://www.security-assessment.com/Whitepapers/0x00_vs_ASP_File_Uploads.pdf