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.
Metrics
Affected Vendors & Products
References
History
No history.
MITRE
Status: PUBLISHED
Assigner: mozilla
Published: 2021-12-08T21:21:41
Updated: 2024-08-04T01:44:23.527Z
Reserved: 2021-08-10T00:00:00
Link: CVE-2021-38507
Vulnrichment
No data.
NVD
Status : Modified
Published: 2021-12-08T22:15:08.947
Modified: 2024-11-21T06:17:16.447
Link: CVE-2021-38507
Redhat