Thunderbird ignored the configuration to require STARTTLS security for an SMTP connection. A MITM could perform a downgrade attack to intercept transmitted messages, or could take control of the authenticated session to execute SMTP commands chosen by the MITM. If an unprotected authentication method was configured, the MITM could obtain the authentication credentials, too. This vulnerability affects Thunderbird < 91.2.
https://bugzilla.mozilla.org/show_bug.cgi?id=1733366
https://www.mozilla.org/security/advisories/mfsa2021-47/
https://www.debian.org/security/2022/dsa-5034
https://lists.debian.org/debian-lts-announce/2022/01/msg00001.html
Source: MITRE
Published: 2021-11-03
Updated: 2022-07-12
Type: NVD-CWE-Other
Base Score: 4.3
Vector: AV:N/AC:M/Au:N/C:P/I:N/A:N
Impact Score: 2.9
Exploitability Score: 8.6
Severity: MEDIUM
Base Score: 5.9
Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
Impact Score: 3.6
Exploitability Score: 2.2
Severity: MEDIUM