Vulnerability · NVD

CVE-2021-38507

CVE-2021-38507, medium severity (CVSS 6.5): 2 tracked apps concerned, all fixed or indeterminable on their current version.

Severity (CVSS): 6.5
Exploitation: 0.8 %
Tracked apps: 2
Still exposed: 0

Published on 2021-12-08

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.

Attack vector : Network No privileges required

Show raw CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N

EPSS 0.80% above median percentile 55.1%

Tracked apps referencing this CVE

For each app: the affected range, the fixing version, and where the tracked app stands today.

Mozilla Firefox Windows winget:Mozilla.Firefox

Affected <94.0 Fixed in 94.0 Latest tracked 157.0 patched
Mozilla Thunderbird Windows winget:Mozilla.Thunderbird

Affected <91.3.0 Fixed in 91.3.0 Latest tracked 157.0 patched

Observed affected builds (23)

91.2.1 91.2.0 91.1.2 91.0.3 78.12.0 78.11.0 78.10.2 78.10.1 78.10.0 78.9.1 78.8.1 78.7.1 78.6.1 78.4.0 78.3.2 78.2.1 78.1.1 78.1.0 78.0.1 78.0 68.10.0 68.9.0 68.8.0

Vulnerable CPE configurations (2)

Vendor	Product	Platform	Versions	CPE 2.3 URI
mozilla	firefox All platforms (wildcard)	All platforms (wildcard)	<94.0	cpe:2.3:a:mozilla:firefox::::::::
mozilla	thunderbird All platforms (wildcard)	All platforms (wildcard)	<91.3.0	cpe:2.3:a:mozilla:thunderbird::::::::

View on NVD ↗ Advisory · bugzilla.mozilla.org Advisory · www.mozilla.org

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