In Apache HTTP Server 2.4.0-2.4.39, a limited cross-site scripting issue was reported affecting the mod_proxy error page. An attacker could cause the link on the error page to be malformed and instead point to a page of their choice. This would only be exploitable where a server was set up with proxying enabled but was misconfigured in such a way that the Proxy Error page was displayed.
https://www.oracle.com/technetwork/security-advisory/cpuoct2019-5072832.html
https://www.oracle.com/security-alerts/cpujul2020.html
https://www.oracle.com/security-alerts/cpujan2020.html
https://www.oracle.com/security-alerts/cpuapr2020.html
https://www.debian.org/security/2019/dsa-4509
https://usn.ubuntu.com/4113-1/
https://support.f5.com/csp/article/K30442259
https://security.netapp.com/advisory/ntap-20190905-0003/
https://security.gentoo.org/glsa/201909-04
https://seclists.org/bugtraq/2019/Oct/24
https://seclists.org/bugtraq/2019/Aug/47
https://lists.debian.org/debian-lts-announce/2019/09/msg00034.html
https://lists.debian.org/debian-lts-announce/2019/08/msg00034.html
https://httpd.apache.org/security/vulnerabilities_24.html
https://access.redhat.com/errata/RHSA-2019:4126
http://www.openwall.com/lists/oss-security/2020/08/08/9
http://www.openwall.com/lists/oss-security/2020/08/08/1
http://www.openwall.com/lists/oss-security/2019/08/15/4
http://lists.opensuse.org/opensuse-security-announce/2019-09/msg00004.html