A crafted S/MIME message consisting of an inner encryption layer and an outer SignedData layer was shown as having a valid digital signature, although the signer might have had no access to the contents of the encrypted message, and might have stripped a different signature from the encrypted message. Previous versions had only suppressed showing a digital signature for messages with an outer multipart/signed layer. This vulnerability affects Thunderbird < 68.1.1.
http://lists.opensuse.org/opensuse-security-announce/2019-10/msg00009.html
http://lists.opensuse.org/opensuse-security-announce/2019-10/msg00010.html
https://bugzilla.mozilla.org/show_bug.cgi?id=1240290
https://lists.debian.org/debian-lts-announce/2019/11/msg00017.html
https://seclists.org/bugtraq/2019/Nov/24
https://usn.ubuntu.com/4202-1/
https://usn.ubuntu.com/4335-1/
Source: MITRE
Published: 2019-09-27
Updated: 2020-08-24
Type: CWE-347
Base Score: 5
Vector: AV:N/AC:L/Au:N/C:N/I:P/A:N
Impact Score: 2.9
Exploitability Score: 10
Severity: MEDIUM
Base Score: 7.5
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
Impact Score: 3.6
Exploitability Score: 3.9
Severity: HIGH