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.
References
Configurations
Configuration 1 (hide)
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Configuration 2 (hide)
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History
No history.
Information
Published : 2021-12-08 22:15
Updated : 2024-11-21 06:17
NVD link : CVE-2021-38507
Mitre link : CVE-2021-38507
CVE.ORG link : CVE-2021-38507
JSON object : View
Products Affected
mozilla
- thunderbird
- firefox
- firefox_esr
debian
- debian_linux
CWE
CWE-346
Origin Validation Error