The fix_hostname function in cURL and libcurl 7.37.0 through 7.41.0 does not properly calculate an index, which allows remote attackers to cause a denial of service (out-of-bounds read or write and crash) or possibly have other unspecified impact via a zero-length host name, as demonstrated by http://:80 and :80. http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2015-3144
