| Name | CVE-2021-38507 |
| 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. |
| Source | CVE (at NVD; CERT, LWN, oss-sec, fulldisc, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more) |
| References | DLA-2863-1, DLA-2874-1, DSA-5026-1, DSA-5034-1 |
The table below lists information on source packages.
| Source Package | Release | Version | Status |
|---|---|---|---|
| firefox (PTS) | sid | 133.0.3-1 | fixed |
| firefox-esr (PTS) | bullseye | 115.14.0esr-1~deb11u1 | fixed |
| bullseye (security) | 128.5.0esr-1~deb11u1 | fixed | |
| bookworm | 128.3.1esr-1~deb12u1 | fixed | |
| bookworm (security) | 128.5.0esr-1~deb12u1 | fixed | |
| trixie | 128.5.0esr-1 | fixed | |
| sid | 128.5.1esr-1 | fixed | |
| thunderbird (PTS) | bullseye | 1:115.12.0-1~deb11u1 | fixed |
| bullseye (security) | 1:128.5.0esr-1~deb11u1 | fixed | |
| bookworm | 1:115.16.0esr-1~deb12u1 | fixed | |
| bookworm (security) | 1:128.5.0esr-1~deb12u1 | fixed | |
| sid, trixie | 1:128.5.2esr-1 | fixed |
The information below is based on the following data on fixed versions.
| Package | Type | Release | Fixed Version | Urgency | Origin | Debian Bugs |
|---|---|---|---|---|---|---|
| firefox | source | (unstable) | 94.0-1 | |||
| firefox-esr | source | stretch | 91.4.1esr-1~deb9u1 | DLA-2863-1 | ||
| firefox-esr | source | bullseye | 91.4.1esr-1~deb11u1 | DSA-5026-1 | ||
| firefox-esr | source | (unstable) | 91.3.0esr-1 | |||
| thunderbird | source | stretch | 1:91.4.1-1~deb9u1 | DLA-2874-1 | ||
| thunderbird | source | buster | 1:91.4.1-1~deb10u1 | DSA-5034-1 | ||
| thunderbird | source | bullseye | 1:91.4.1-1~deb11u1 | DSA-5034-1 | ||
| thunderbird | source | (unstable) | 1:91.3.0-1 |
https://www.mozilla.org/en-US/security/advisories/mfsa2021-48/#CVE-2021-38507
https://www.mozilla.org/en-US/security/advisories/mfsa2021-49/#CVE-2021-38507
https://www.mozilla.org/en-US/security/advisories/mfsa2021-50/#CVE-2021-38507