PT-2021-4950 · Mozilla+9 · Firefox Esr+11
Takeshi Terada
·
Published
2021-11-02
·
Updated
2024-12-12
·
CVE-2021-38507
CVSS v3.1
6.5
Medium
| Vector | AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N |
Name of the Vulnerable Software and Affected Versions
Firefox versions prior to 94
Thunderbird versions prior to 91.3
Firefox ESR versions prior to 91.3
Description
The issue is related to the Opportunistic Encryption feature of HTTP2, which allows a connection to be upgraded to TLS while retaining the visual properties of an HTTP connection. A network attacker could exploit this by forwarding a connection from the browser to a different port, causing the browser to treat the content as same-origin with HTTP. This could allow a remote attacker to bypass security restrictions.
Recommendations
For Firefox versions prior to 94, disable the Opportunistic Encryption feature.
For Thunderbird versions prior to 91.3, disable the Opportunistic Encryption feature.
For Firefox ESR versions prior to 91.3, disable the Opportunistic Encryption feature.
Exploit
Fix
Origin Validation Error
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Related Identifiers
Affected Products
Alt Linux
Almalinux
Astra Linux
Centos
Firefox
Firefox Esr
Linuxmint
Red Hat
Rocky Linux
Suse
Thunderbird
Ubuntu