When the default servlet in Apache Tomcat versions 9.0.0.M1 to 9.0.11, 8.5.0 to 8.5.33 and 7.0.23 to 7.0.90 returned a redirect to a directory (e.g. redirecting to '/foo/' when the user requested '/foo') a specially crafted URL could be used to cause the redirect to be generated to any URI of the attackers choice.
https://www.oracle.com/technetwork/security-advisory/cpuoct2019-5072832.html
https://www.oracle.com/technetwork/security-advisory/cpujul2019-5072835.html
https://www.oracle.com/technetwork/security-advisory/cpujan2019-5072801.html
https://www.oracle.com/technetwork/security-advisory/cpuapr2019-5072813.html
https://www.oracle.com/security-alerts/cpujan2020.html
https://www.oracle.com/security-alerts/cpuapr2020.html
https://www.debian.org/security/2019/dsa-4596
https://usn.ubuntu.com/3787-1/
https://security.netapp.com/advisory/ntap-20181014-0002/
https://seclists.org/bugtraq/2019/Dec/43
https://lists.debian.org/debian-lts-announce/2018/10/msg00006.html
https://lists.debian.org/debian-lts-announce/2018/10/msg00005.html
https://kc.mcafee.com/corporate/index?page=content&id=SB10284
https://access.redhat.com/errata/RHSA-2019:1529
https://access.redhat.com/errata/RHSA-2019:0485
https://access.redhat.com/errata/RHSA-2019:0131
https://access.redhat.com/errata/RHSA-2019:0130
http://www.securityfocus.com/bid/105524
http://packetstormsecurity.com/files/163456/Apache-Tomcat-9.0.0M1-Open-Redirect.html
http://lists.opensuse.org/opensuse-security-announce/2019-07/msg00056.html
http://lists.opensuse.org/opensuse-security-announce/2019-06/msg00030.html