Red Hat: CVE-2021-38507: CVE-2021-38507 Mozilla: Opportunistic Encryption in HTTP2 could be used to bypass the Same-Origin-Policy on services hosted on other ports (Multiple Advisories)
Description
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. This vulnerability affects Firefox < 94, Thunderbird < 91.3, and Firefox ESR < 91.3.
Solution(s)
- redhat-upgrade-firefox
- redhat-upgrade-firefox-debuginfo
- redhat-upgrade-firefox-debugsource
- redhat-upgrade-thunderbird
- redhat-upgrade-thunderbird-debuginfo
- redhat-upgrade-thunderbird-debugsource
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