CVE - CVE-2021-38507

CVE-ID
CVE-2021-38507	Learn more at National Vulnerability Database (NVD) • CVSS Severity Rating • Fix Information • Vulnerable Software Versions • SCAP Mappings • CPE Information
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.
References
Note: References are provided for the convenience of the reader to help distinguish between vulnerabilities. The list is not intended to be complete.
DEBIAN:DSA-5026 URL:https://www.debian.org/security/2021/dsa-5026 DEBIAN:DSA-5034 URL:https://www.debian.org/security/2022/dsa-5034 GENTOO:GLSA-202202-03 URL:https://security.gentoo.org/glsa/202202-03 GENTOO:GLSA-202208-14 URL:https://security.gentoo.org/glsa/202208-14 MISC:https://bugzilla.mozilla.org/show_bug.cgi?id=1730935 URL:https://bugzilla.mozilla.org/show_bug.cgi?id=1730935 MISC:https://www.mozilla.org/security/advisories/mfsa2021-48/ URL:https://www.mozilla.org/security/advisories/mfsa2021-48/ MISC:https://www.mozilla.org/security/advisories/mfsa2021-49/ URL:https://www.mozilla.org/security/advisories/mfsa2021-49/ MISC:https://www.mozilla.org/security/advisories/mfsa2021-50/ URL:https://www.mozilla.org/security/advisories/mfsa2021-50/ MLIST:[debian-lts-announce] 20211229 [SECURITY] [DLA 2863-1] firefox-esr security update URL:https://lists.debian.org/debian-lts-announce/2021/12/msg00030.html MLIST:[debian-lts-announce] 20220104 [SECURITY] [DLA 2874-1] thunderbird security update URL:https://lists.debian.org/debian-lts-announce/2022/01/msg00001.html
Assigning CNA
Mozilla Corporation
Date Record Created
20210810	Disclaimer: The record creation date may reflect when the CVE ID was allocated or reserved, and does not necessarily indicate when this vulnerability was discovered, shared with the affected vendor, publicly disclosed, or updated in CVE.
Phase (Legacy)
Assigned (20210810)
Votes (Legacy)

Comments (Legacy)

Proposed (Legacy)
N/A
This is an record on the CVE List, which provides common identifiers for publicly known cybersecurity vulnerabilities.
Search CVE Using Keywords: You can also search by reference using the CVE Reference Maps.
For More Information: CVE Request Web Form (select "Other" from dropdown)