The HTTP Inspect preprocessor (http_inspect) in Snort 2.4.0 through 2.4.4 allows remote attackers to bypass "uricontent" rules via a carriage return (\r) after the URL and before the HTTP declaration.
https://exchange.xforce.ibmcloud.com/vulnerabilities/26855
http://www.vupen.com/english/advisories/2006/2119
http://www.snort.org/pub-bin/snortnews.cgi#431
http://www.securityfocus.com/archive/1/435872/100/0/threaded
http://www.securityfocus.com/archive/1/435797/100/0/threaded
http://www.securityfocus.com/archive/1/435734/100/0/threaded
http://www.securityfocus.com/archive/1/435600/100/0/threaded
http://securityreason.com/securityalert/1018
http://secunia.com/advisories/20766
http://secunia.com/advisories/20413
http://marc.info/?l=snort-devel&m=114909074311462&w=2
http://lists.suse.com/archive/suse-security-announce/2006-Jun/0008.html