The Opportunistic Encryption feature of HTTP2 (RFC 8164) allows a connection to be transparently upgraded to TLS while retaining the visual properties of an HTTP connection, including being same-origin with unencrypted connections on port 80. However, if a second encrypted port on the same IP address (e.g. port 8443) did not opt-in to opportunistic encryption; a network attacker could forward a connection from the browser to port 443 to port 8443, causing the browser to treat the content of port 8443 as same-origin with HTTP. This was resolved by disabling the Opportunistic Encryption feature, which had low usage. External Reference: https://www.mozilla.org/en-US/security/advisories/mfsa2021-49/#CVE-2021-38507
This issue has been addressed in the following products: Red Hat Enterprise Linux 7 Via RHSA-2021:4116 https://access.redhat.com/errata/RHSA-2021:4116
This issue has been addressed in the following products: Red Hat Enterprise Linux 8 Via RHSA-2021:4123 https://access.redhat.com/errata/RHSA-2021:4123
This bug is now closed. Further updates for individual products will be reflected on the CVE page(s): https://access.redhat.com/security/cve/cve-2021-38507
This issue has been addressed in the following products: Red Hat Enterprise Linux 8.1 Extended Update Support Via RHSA-2021:4133 https://access.redhat.com/errata/RHSA-2021:4133
This issue has been addressed in the following products: Red Hat Enterprise Linux 8.2 Extended Update Support Via RHSA-2021:4132 https://access.redhat.com/errata/RHSA-2021:4132
This issue has been addressed in the following products: Red Hat Enterprise Linux 8 Via RHSA-2021:4130 https://access.redhat.com/errata/RHSA-2021:4130
This issue has been addressed in the following products: Red Hat Enterprise Linux 7 Via RHSA-2021:4134 https://access.redhat.com/errata/RHSA-2021:4134
This issue has been addressed in the following products: Red Hat Enterprise Linux 8.1 Extended Update Support Via RHSA-2021:4607 https://access.redhat.com/errata/RHSA-2021:4607
This issue has been addressed in the following products: Red Hat Enterprise Linux 8.2 Extended Update Support Via RHSA-2021:4605 https://access.redhat.com/errata/RHSA-2021:4605