Bugzilla 2.16.10, 2.17 through 2.18.4, and 2.20 does not properly handle certain characters in the mostfreqthreshold parameter in duplicates.cgi, which allows remote attackers to trigger a SQL error.
https://exchange.xforce.ibmcloud.com/vulnerabilities/42802
http://www.vupen.com/english/advisories/2006/0692
http://www.securityfocus.com/archive/1/425584/100/0/threaded