Mantis before 0.19.4 allows remote attackers to bypass the file upload size restriction by modifying the max_file_size parameter to (1) bug_file_add.php, (2) bug_report.php, (3) bug_report_advanced_page.php, and (4) proj_doc_add_page.php.
http://www.vupen.com/english/advisories/2005/3064
http://www.securityfocus.com/bid/16046/
http://www.gentoo.org/security/en/glsa/glsa-200512-12.xml
http://www.debian.org/security/2005/dsa-944
http://sourceforge.net/project/shownotes.php?release_id=377932&group_id=14963
http://secunia.com/advisories/18481