An issue was discovered in OpenStack Horizon before 15.3.2, 16.x before 16.2.1, 17.x and 18.x before 18.3.3, 18.4.x, and 18.5.x. There is a lack of validation of the "next" parameter, which would allow someone to supply a malicious URL in Horizon that can cause an automatic redirect to the provided malicious URL.
https://www.debian.org/security/2020/dsa-4820
https://security.openstack.org/ossa/OSSA-2020-008.html
https://review.opendev.org/c/openstack/horizon/+/758843/
https://review.opendev.org/c/openstack/horizon/+/758841/