The client_host function in parsers.c in Privoxy before 3.0.24 allows remote attackers to cause a denial of service (invalid read and crash) via an empty HTTP Host header.
http://www.privoxy.org/announce.txt
http://www.openwall.com/lists/oss-security/2016/01/22/3
http://www.openwall.com/lists/oss-security/2016/01/21/4
http://www.debian.org/security/2016/dsa-3460
http://lists.fedoraproject.org/pipermail/package-announce/2016-February/176492.html
http://lists.fedoraproject.org/pipermail/package-announce/2016-February/176475.html
http://ijbswa.cvs.sourceforge.net/viewvc/ijbswa/current/parsers.c?r1=1.302&r2=1.303