CVE-2021-38507

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.

Link	Resource
https://www.mozilla.org/security/advisories/mfsa2021-50/	Vendor Advisory
https://bugzilla.mozilla.org/show_bug.cgi?id=1730935	Issue Tracking Permissions Required
https://www.mozilla.org/security/advisories/mfsa2021-49/	Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2021-48/	Vendor Advisory
https://www.debian.org/security/2021/dsa-5026	Third Party Advisory
https://lists.debian.org/debian-lts-announce/2021/12/msg00030.html	Mailing List Third Party Advisory
https://www.debian.org/security/2022/dsa-5034	Third Party Advisory
https://lists.debian.org/debian-lts-announce/2022/01/msg00001.html	Mailing List Third Party Advisory
https://security.gentoo.org/glsa/202202-03	Third Party Advisory
https://security.gentoo.org/glsa/202208-14	Third Party Advisory

Configuration 1

cpe:2.3:a:mozilla:firefox_esr:*:*:*:*:*:*:*:* cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:* cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:* cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:* cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:* cpe:2.3:o:debian:debian_linux:11.0:*:*:*:*:*:*:*

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Published : 2021-12-08 10:15

Updated : 2022-12-09 03:54

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NVD link : CVE-2021-38507

Mitre link : CVE-2021-38507

No products.

CWE-346