core/string_api.php in MantisBT before 1.2.18 does not properly categorize URLs when running under the web root, which allows remote attackers to conduct open redirect and phishing attacks via a crafted URL in the return parameter to login_page.php.
seclists.org/oss-sec/2014/q4/931
secunia.com/advisories/62101
www.debian.org/security/2015/dsa-3120
www.openwall.com/lists/oss-security/2014/12/03/11
www.securityfocus.com/bid/71478
exchange.xforce.ibmcloud.com/vulnerabilities/99128
github.com/mantisbt/mantisbt/commit/e66ecc9f
www.mantisbt.org/bugs/view.php?id=17648