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CVE-2021-38507

Published: 3 November 2021

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.

Notes

AuthorNote
tyhicks
mozjs contains a copy of the SpiderMonkey JavaScript engine
Priority

Medium

CVSS 3 base score: 6.5

Status

Package Release Status
firefox
Launchpad, Ubuntu, Debian
bionic
Released (94.0+build3-0ubuntu0.18.04.1)
focal
Released (94.0+build3-0ubuntu0.20.04.1)
hirsute
Released (94.0+build3-0ubuntu0.21.04.1)
impish
Released (94.0+build3-0ubuntu0.21.10.1)
jammy
Released (94.0+build3-0ubuntu1)
kinetic
Released (94.0+build3-0ubuntu1)
trusty Does not exist

upstream
Released (94)
xenial Needed

mozjs38
Launchpad, Ubuntu, Debian
bionic Needs triage

focal Does not exist

hirsute Does not exist

impish Does not exist

jammy Does not exist

kinetic Does not exist

trusty Does not exist

upstream Needs triage

xenial Does not exist

mozjs52
Launchpad, Ubuntu, Debian
bionic Needs triage

focal Needs triage

hirsute Does not exist

impish Does not exist

jammy Does not exist

kinetic Does not exist

trusty Does not exist

upstream Needs triage

xenial Does not exist

mozjs68
Launchpad, Ubuntu, Debian
bionic Does not exist

focal Needs triage

hirsute Does not exist

impish Does not exist

jammy Does not exist

kinetic Does not exist

trusty Does not exist

upstream Needs triage

xenial Does not exist

mozjs78
Launchpad, Ubuntu, Debian
bionic Does not exist

focal Does not exist

hirsute Ignored
(reached end-of-life)
impish Ignored
(reached end-of-life)
jammy Needs triage

kinetic Needs triage

trusty Does not exist

upstream Needs triage

xenial Does not exist

thunderbird
Launchpad, Ubuntu, Debian
bionic
Released (1:91.5.0+build1-0ubuntu0.18.04.1)
focal
Released (1:91.5.0+build1-0ubuntu0.20.04.1)
hirsute Ignored
(reached end-of-life)
impish
Released (1:91.3.1+build1-0ubuntu0.21.10.1)
jammy
Released (1:91.3.1+build1-0ubuntu1)
kinetic
Released (1:91.3.1+build1-0ubuntu1)
trusty Does not exist

upstream
Released (91.3)
xenial Needed