When you visit a page where you need to login, Plone 2.5-5.1rc1 sends you to the login form with a ‘came_from’ parameter set to the previous url. After you login, you get redirected to the page you tried to view before. An attacker might try to abuse this by letting you click on a specially crafted link. You would login, and get redirected to the site of the attacker, letting you think that you are still on the original Plone site. Or some javascript of the attacker could be executed. Most of these types of attacks are already blocked by Plone, using the isURLInPortal
check to make sure we only redirect to a page on the same Plone site. But a few more ways of tricking Plone into accepting a malicious link were discovered, and fixed with this hotfix.
github.com/plone/Products.CMFPlone
github.com/plone/Products.CMFPlone/commit/05a943ecbcdda56bacc93b55c9e2e908d8a7dfab
github.com/plone/Products.CMFPlone/commit/0e50e1e67ea3b6d3187f78cb1a1628081f654d3b
github.com/plone/Products.CMFPlone/commit/236b62b756ff46a92783b3897e717dfb15eb07d8
github.com/plone/Products.CMFPlone/commit/7db5b2c8fb684055987b8c4fdedc29289bd26373
github.com/plone/Products.CMFPlone/issues/2232
github.com/plone/Products.CMFPlone/pull/2233
github.com/plone/Products.CMFPlone/pull/2234
github.com/plone/Products.CMFPlone/pull/2235
github.com/plone/Products.CMFPlone/pull/2236
nvd.nist.gov/vuln/detail/CVE-2017-1000481
plone.org/security/hotfix/20171128/open-redirection-on-login-form