CVE-2021-38507
- State
- Published
- Severity
- Not scored
- Published
- Dec 8, 2021
- Updated
- Aug 4, 2024
- Reserved
- Aug 10, 2021
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.
Scores
The record has no CVSS score.
Weaknesses
The record names no weakness.
Affected Products
| Product | Versions |
|---|---|
FirefoxMozilla |
|
ThunderbirdMozilla |
|
Firefox ESRMozilla |
|
References
- https://www.mozilla.org/security/advisories/mfsa2021-49/
- https://www.mozilla.org/security/advisories/mfsa2021-50/
- https://www.mozilla.org/security/advisories/mfsa2021-48/
- https://bugzilla.mozilla.org/show_bug.cgi?id=1730935
- DSA-5026vendor-advisory
- [debian-lts-announce] 20211229 [SECURITY] [DLA 2863-1] firefox-esr security updatemailing-list
- DSA-5034vendor-advisory
- [debian-lts-announce] 20220104 [SECURITY] [DLA 2874-1] thunderbird security updatemailing-list
- GLSA-202202-03vendor-advisory
- GLSA-202208-14vendor-advisory
Every record here comes from the CVE Program’s CVE List. © 1999–2026 The MITRE Corporation. CVE is a registered trademark of The MITRE Corporation. The records are reproduced under the CVE Program terms of use.