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.
References
| 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 Vendor Advisory |
| 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 | |
| https://www.debian.org/security/2022/dsa-5034 | |
| https://lists.debian.org/debian-lts-announce/2022/01/msg00001.html | |
| https://security.gentoo.org/glsa/202202-03 |
Information
Published : 2021-12-08 22:15
Updated : 2022-02-22 01:15
NVD link : CVE-2021-38507
Mitre link : CVE-2021-38507
JSON object : View
Products Affected
mozilla
- firefox_esr
- thunderbird
- firefox
debian
- debian_linux
CWE
CWE-346
Origin Validation Error