A vulnerability was found in Apache HTTP Server 2.4.0 to 2.4.38. When the path component of a request URL contains multiple consecutive slashes ('/'), directives such as LocationMatch and RewriteRule must account for duplicates in regular expressions while other aspects of the servers processing will implicitly collapse them.
https://www.oracle.com/technetwork/security-advisory/cpuoct2019-5072832.html
https://www.oracle.com/technetwork/security-advisory/cpujul2019-5072835.html
https://www.oracle.com/security-alerts/cpujul2022.html
https://www.oracle.com/security-alerts/cpujul2020.html
https://www.oracle.com/security-alerts/cpuapr2020.html
https://www.debian.org/security/2019/dsa-4422
https://usn.ubuntu.com/3937-1/
https://support.hpe.com/hpsc/doc/public/display?docLocale=en_US&docId=emr_na-hpesbux03950en_us
https://support.f5.com/csp/article/K44591505
https://security.netapp.com/advisory/ntap-20190625-0007/
https://seclists.org/bugtraq/2019/Apr/5
https://lists.debian.org/debian-lts-announce/2019/04/msg00008.html
https://httpd.apache.org/security/vulnerabilities_24.html
https://access.redhat.com/errata/RHSA-2020:0251
https://access.redhat.com/errata/RHSA-2020:0250
https://access.redhat.com/errata/RHSA-2019:4126
https://access.redhat.com/errata/RHSA-2019:3436
https://access.redhat.com/errata/RHSA-2019:2343
http://www.securityfocus.com/bid/107670
http://www.openwall.com/lists/oss-security/2019/04/02/6
http://lists.opensuse.org/opensuse-security-announce/2019-04/msg00084.html
http://lists.opensuse.org/opensuse-security-announce/2019-04/msg00061.html
http://lists.opensuse.org/opensuse-security-announce/2019-04/msg00051.html