Plone Open Redirection vulnerability via next parameter

The isURLInPortal method in the URLTool class in inportal.py in Plone 2.1 through 4.1, 4.2.x through 4.2.5, and 4.3.x through 4.3.1 treats URLs starting with a space as a relative URL, which allows remote attackers to bypass the allowexternalloginsites filtering property, redirect users to...