LibHTP is a security-aware parser for the HTTP protocol. Crafted traffic can cause excessive processing time of HTTP headers, leading to denial of service. This issue is addressed in 0.5.46.
In OISF LibHTP before 0.5.31, as used in Suricata 4.1.4 and other products, an HTTP protocol parsing error causes the http_header signature to not alert on a response with a single \r\n ending.