A flaw during verification of certain S/MIME signatures causes emails to be shown in Thunderbird as having a valid digital signature, even if the shown message contents aren't covered by the signature. The flaw allows an attacker to reuse a valid S/MIME signature to craft an email message with arbitrary content. This vulnerability affects Thunderbird < 60.5.1.
http://lists.opensuse.org/opensuse-security-announce/2019-04/msg00043.html
http://packetstormsecurity.com/files/152703/Johnny-You-Are-Fired.html
http://seclists.org/fulldisclosure/2019/Apr/38
http://www.openwall.com/lists/oss-security/2019/04/30/4
https://access.redhat.com/errata/RHSA-2019:1144
https://bugzilla.mozilla.org/show_bug.cgi?id=1507218
https://github.com/RUB-NDS/Johnny-You-Are-Fired
https://github.com/RUB-NDS/Johnny-You-Are-Fired/blob/master/paper/johnny-fired.pdf
Source: MITRE
Published: 2019-04-26
Updated: 2019-06-03
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: 5.3
Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
Impact Score: 1.4
Exploitability Score: 3.9
Severity: MEDIUM