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
| Author | Note |
|---|---|
| tyhicks | mozjs contains a copy of the SpiderMonkey JavaScript engine |
Priority
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
|
Severity score breakdown
| Parameter | Value |
|---|---|
| Base score | 6.5 |
| Attack vector | Network |
| Attack complexity | Low |
| Privileges required | None |
| User interaction | Required |
| Scope | Unchanged |
| Confidentiality | None |
| Integrity impact | High |
| Availability impact | None |
| Vector | CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N |
References
- https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-38507
- 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://ubuntu.com/security/notices/USN-5131-1
- https://ubuntu.com/security/notices/USN-5152-1
- https://ubuntu.com/security/notices/USN-5248-1
- NVD
- Launchpad
- Debian