CVE-2021-38507

 

Published at: - 08-12-2021 11:15

Last modified: - 24-09-2022 03:03

Total changes: - 14

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.

Common Vulnerability Scoring System (CVSS)

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

 

Verification logic

 

Reference

• https://www.mozilla.org/security/advisories/mfsa2021-50/
• https://bugzilla.mozilla.org/show_bug.cgi?id=1730935
• https://www.mozilla.org/security/advisories/mfsa2021-49/
• https://www.mozilla.org/security/advisories/mfsa2021-48/
• DSA-5026-Third Party Advisory
• [debian-lts-announce] 20211229 [SECURITY] [DLA 2863-1] firefox-esr security update-Mailing List, Third Party Advisory
• DSA-5034-Third Party Advisory
• [debian-lts-announce] 20220104 [SECURITY] [DLA 2874-1] thunderbird security update-Mailing List, Third Party Advisory
• GLSA-202202-03-Third Party Advisory
• GLSA-202208-14-

 

Keywords

NVD

 

CVE-2021-38507

 

CVE

 

Common vulnerabilities & exposures

 

CVSS

 

Common vulnerability scoring system

 

Security

 

Vulnerabilities

 

Exposures